1. Structure Programming Programming in Java
Instructed and enhanced by
Dr. Safia Abbas
Computer Science Department
Faculty of Computer and Information Sciences
Ain Shams University
Prepared By
Dr. safia abbas

2. The Course Instructor: Dr. safia abbas Text Book:
Paul Deitel and Harvey Deitel.
“Java-How to Program. 9th edition,
Pearson,2013.”

3. Other (Online) Resources
How to Think Like a Computer Scientist
Introduction to Programming Using Java, 5th Edition
Thinking in Java, 3rd Edition
Sun Java Tutorial
The Java API

4. Course Contents Introduction. Variables, types and expressions.
Functions and procedural abstraction.
Input/ output and streams.
Branch and loop statements.
Arrays and strings.
Pointers.
Recursions.

5. Lecture 1: Agenda
• Introduction - computer hardware & Programming Languages
• First Program
• Output Using pint
• Directives
• Comments
• Integer Variables
• Input with Scanner
• Variable Names
• Arithmetic Expressions
• The arithmetic assignment operators
• Character Variables
• Floating Point Types
• const Qualifier
• Type bool
• The setw Manipulator
• Variable Type Summary
• Type Conversion
• Increment Operators
• Math Library Functions

6. Main computer components
A computer is a machine that can perform computation. a computation involves the following three components:
Input: The user gives a set of input data.
Processing: The input data is processed by a well-defined and finite sequence of steps.
Output: Some data available from the processing step are output to the user.
Usually, computations are carried out to solve some meaningful and useful problems. One supplies some input instances for the problem, which are then analyzed in order to obtain the answers for the instances.

7. Why digital computers & problems types
Usually, computer perform computations in order to solve some meaningful and useful problems faster and more accurately. One supplies some input instances for the problem, which are then analyzed in order to obtain the answers for the instances.
Types of problems
Functional problems A set of arguments a1,a2,...,are send to Some function, as f(a1,a2,...,an), which in turn calculate the arguments and output to the user.
Decision problems These form a special class of functional problems whose outputs are "yes" and "no" (or "true" and "false", or "1" and "0", etc).
Search problems Given an input object, one tries to locate some particular configuration pertaining to the object and outputs the located configuration, or "failure" if no configuration can be located.
Optimization problems Given an object, a configuration and a criterion for goodness, one finds and reports the configuration pertaining to the object, that is best with respect to the different existing paths.

8. How does a program run in a computer?
The inputs, the intermediate values and the instructions defining the processing stage reside in the (main) memory. In order to separate data from instructions the memory is divided into two parts:
Data area The data area stores the variables needed for the processing stage. The values stored in the data area can be read, written and modified by the CPU.
Instruction area The instruction area stores a sequence of instructions that define the steps of the program. Under the control of a clock, the computer carries out a fetch-decode-execute cycle in which instructions are fetched one-by-one from the instruction area to the CPU, decoded in the control unit and executed in the ALU. The CPU understands only a specific set of instructions. The instructions stored in memory must conform to this specification.

9. How does a program run in a computer?

10. What is programming?
Programming is a process done by programmers to instruct a computer on how to do a task .
It is Planning or scheduling a sequence of steps for a computer to follow to perform a task.
Basically, telling a computer what to do and how to do it.
A program is :
A sequence of steps to be performed by a computer.
Expressed in a computer language.

11. Programming Techniques
2017/4/23
Programming Techniques
Unstructured Programming
Procedural Programming
Modular & Structural Programming
Abstract Data Type
Object-Oriented Programming 11

12. Unstructured Programming
2017/4/23
Unstructured Programming
Small and (simple?) programs.
Consists only of one main program.
Here ``main program'' stands for a sequence of commands or statements which modify data which is global throughout the whole program.
Main Program
Data 12

13. 2017/4/23
Drawbacks
This programming technique can only be used in a very small program. Why?
For example, if the same statement sequence is needed at different locations within the program, the sequence must be copied. If an error needed to be modified, every copy needs to be modified.
 This has lead to the idea to extract these sequences (procedure), name them and offering a technique to call and return from these procedures. 13

14. Programming Techniques
2017/4/23
Programming Techniques
Unstructured Programming
Procedural Programming
Modular & Structural Programming
Abstract Data Type
Object-Oriented Programming 14

15. Procedural Programming
2017/4/23
Procedural Programming
With procedural programming, you are able to combine sequences of calling statements into one single place.
A procedure call is used to invoke the procedure. After the sequence is processed, flow of control proceeds right after the position where the call was made .
Main
Program
Procedure 15

16. 2017/4/23
Procedures
With parameters and sub-procedures (procedures of procedures) , programs can now be written more structured and with less errors.
For example, if a procedure is correct, every time it is used it produces correct results.
Consequently, in cases of errors you can narrow your search to those places which are not proven to be correct. 16

17. Procedure Program view
2017/4/23
Procedure Program view
Now a program can be viewed as a sequence of procedure calls.
The main program is responsible to pass data to the individual calls, the data is processed by the procedures and the resulting data is presented.
Thus, the flow of data can be illustrated as a hierarchical graph, a tree. 17

18. Procedure Program view
2017/4/23
Procedure Program view
Main Program
Data
Procedure3
Procedure1
Procedure2 18

19. Programming Techniques
2017/4/23
Programming Techniques
Unstructured Programming
Procedural Programming
Modular & Structural Programming
Abstract Data Type
Object-Oriented Programming
Will be discussed next year 19

20. Modular Programming
2017/4/23
Modular programming is subdividing your program into separate subprograms.
Procedures of a common functionality are grouped together into separate modules.
A program no longer consists of only one single part. It is now divided into several smaller parts which interact through procedure calls.
The main program coordinates calls to procedures in separate modules and hands over appropriate data as parameters. 20

21. Main Program (Also a module)
2017/4/23
Main Program (Also a module)
Data
Module1 +
Module2 +
Data
Data
Data1
Data1
Data
Data2
Procedure2
Procedure3
Procedure1 21

22. Structured Programming
2017/4/23
Structured Programming
A subset of procedural programming that enforces a logical structure on the program being written to make it more efficient and easier to understand and modify. “organizing considering time and space”
Certain languages such as Ada, and Pascal were designed with features that encourage or enforce a logical program 22

23. Structured Programming
2017/4/23
Structured Programming
Basic structures for programming?
Three Types of Structures in a structured program
-Statement sequence(s1,s2,…,sn)
-Branch(if-then-else)
-Loop(for,do, and while loops)
- Keep modules!!! 23

24. Programming languages classes?

25. Programming Languages
There are many different programming languages, and many ways to classify them. For example,
"high-level" programming languages are languages whose syntax is relatively close to natural language,
whereas the syntax of "low-level" languages includes many technical references to the (0's and 1's, etc.)
C is in many ways hard to categories. Compared to assembly language it is high-level, but it nevertheless includes many low-level facilities to directly manipulate the computer's memory.

26. high – level languages Are designed to be easy to read and write
Use more complicated instructions than the CPU can follow
Must be translated to zeros and ones for the CPU to execute a program

27. Machine, Assembler and high level language
Machine language is a numeric language specifically understood by a computer’s processor (the CPU).
Assembly language consist of statements written with short mnemonics such as ADD, MOV, ….It has a one-to- one relationship with machine language instructions
High level language ( such as C++ and Java) has a one–to–many relationship with machine/assembly language instructions

28. How computers understand the instruction?
Programs are written in a programming language, then translated into machine code by a compiler and linker so that the computer can execute it directly or run it line by line (interpreted) by an interpreter program.

29. Linkers Compilers Translate high-level language to machine language
A Linker combines
The object code for the programs we write
And
The object code for the pre-compiled routines
Into
The machine language program, the CPU can run (executable program)

30. Agenda • Introduction - computer hardware & Programming Languages
• First Program
• Output Using print
• Directives
• Comments
• Integer Variables
• Input with scanner
• Variable Names
• Arithmetic Expressions
• The arithmetic assignment operators

31. Type all carefully and save it to a file named Welcome.java
The First Java Program
Type all carefully and save it to a file named Welcome.java
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!");
} // end method main
} // end class welcome

32. Java program source files (.java) contain definition of classes
The First Java Program
Java program source files (.java) contain definition of classes
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!");
} // end method main
} // end class welcome

33. The class name or identifier
The First Java Program
The class name or identifier
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!");
} // end method main
} // end class welcome

34. Class name or identifier
class names begin with a capital letter and capitalize the first letter of each word they include (e.g., SampleClassName).
A class name is an identifier—a series of characters consisting of letters, digits, underscores (_) and dollar signs ($) that does not begin with a digit and does not contain spaces.
Ex. valid identifiers such as
Welcome1, $value,_value, m_inputField1 and button7.
Ex. Invalid identifiers such as
7button not a valid identifier because start with digit
input field not a valid identifier because it contains a space
identifier that does not begin with a capital letter is not a class name.
Java is case sensitive—uppercase and lowercase letters are distinct—so value and Value are different.

35. Curly braces pair enclose a block of code, class Welcome here
The First Java Program
Curly braces pair enclose a block of code, class Welcome here
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!"); }
Don’t miss me!

36. Curly braces pair enclose a block of code, method main() here
The First Java Program
Curly braces pair enclose a block of code, method main() here
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!"); }
Don’t miss me!

37. The First Java Program class Welcome { /* The Welcome Program
This is a block of comments, for human, not for computer
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!"); }
It explains to you what happens

38. /* and */ pair encloses a comment block
The First Java Program
/* and */ pair encloses a comment block
(over several lines)
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!");
} // end of method main
} // end of class
Don’t miss me!
One line comment

39. This is a method of the class Welcome, named main()
The First Java Program
This is a method of the class Welcome, named main()
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!"); }

40. Declaring a method
The parentheses after the identifier main indicate that it’s a program building block called a method.
Java class declarations can contain one or more methods.
one of the methods must be called main and must be defined as shown previously otherwise, the JVM will not execute the application

41. There MUST be a pair of parentheses following ALL method names
The First Java Program
There MUST be a pair of parentheses following ALL method names
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!"); }
Don’t miss me!

42. The First Java Program class Welcome { /* The Welcome Program
A method may take some input from the caller, formally known as arguments or parameters
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!"); }

43. The First Java Program class Welcome { /* The Welcome Program
A method may give some output to the caller too, known as return value
void means no return value
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!"); }

44. The First Java Program class Welcome { /* The Welcome Program
The static keyword before a method definition indicates this is a class method
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!"); }

45. This method is a public one, others can call me.
The First Java Program
This method is a public one, others can call me.
class Welcome {
/* The Welcome Program Illustrates a simple program
displaying a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!"); }

46. Standard properties of the main() method
The First Java Program
Standard properties of the main() method
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!"); }

47. The First Java Program class Welcome { /* The Welcome Program
A statement (instruction) to display a message “standard output object”
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!"); }
System.out.println( "Welcome\n to\n Java\n Programming!" );

48. Selecting method print
Class System, defined in the Standard Package of java
Output stream object, it is member of System
System . Out . println(“string");
Method member of Out
Selects an individual class member of System
Selects an individual class member of Out
Parameter of Print method

49. After every statement, there must be a semi-colon!
The First Java Program
After every statement, there must be a semi-colon!
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!"); }

50. The First Java Program class Welcome { /* The Welcome Program
How to ask the computer to act according to the instructions in this program?
class Welcome {
/* The Welcome Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.println("Welcome to Java!"); }

52. class Welcome2 {
/* The Welcome2 Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.print( "Welcome to " );
System.out.println( "Java Programming!" ); }
The out put will be
Welcome to java programming

53. class Welcome3 {
/* The Welcome3 Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.print( "Welcome\nto" );
System.out.println( "Java Programming!" ); }
The out put will be
Welcome
to java programming 

54. Format pacifiers begin with %
Displaying Text with printf
Format pacifiers begin with %
class Welcome3 {
/* The Welcome3 Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.printf("%s\n%s\n",
"Welcome to", "Java Programming!"); }
The output
Welcome to
Java Programming!
Place holder for sting

55. What do we do with it? Java program has five steps to be executed
Creating a program.
Compiling a Java program into byte codes.
Loading program into memory.
Byte code verification.
Execution.

56. Creating a program consists of editing a file with an editor program.
Type a Java program (typically referred to as source code) using the editor,
Use any text editor you like (preferred IDEs environment)
Make any necessary corrections and save the program on a secondary storage device, such as your hard drive. save as Welcome.java
A file name ending with the .java extension indicates that the file contains the Java source code.

57. Integrated Development Environments (IDEs)
is a software application that provides comprehensive facilities to computer programmers for software development.
An IDE normally consists of:
a source code editor
build automation tools
a debugger
Some IDEs contain compiler, interpreter, or both, such as Eclipse; others do not,
An easy way to find where the compiler thinks you’ve gone wrong
Examples: NetBeans, Eclipse, Together,…

58. Compiling a Java program into byte codes
use the command javac (the Java compiler) to compile a program.
For example, to compile a program called Welcome.java, you’d type in the command prompet javac Welcome.java
the compiler produces a .class file called Welcome.class that contains the compiled version of the program.
The Java compiler translates Java source code into bytecodes that represent the tasks to be executed.
Bytecodes are executed by the Java Virtual Machine (JVM)—a part of the JDK and the foundation of the Java platform.
The JVM is one of the most widely used virtual machines that its execution can be used on all those platforms.
JVM is unlike machine language, which is dependent on specific computer hardware, bytecodes are platform independent

59. Loading program into memory
the JVM places the program in memory to execute it—this is known as loading.
The JVM’s class loader takes the .class files containing the program’s bytecodes and transfers them to primary memory.

60. Byte code verification
as the classes are loaded, the bytecode verifier examines their bytecodes to ensure that they’re valid and do not violate Java’s security restrictions

61. Execution/Running.
the JVM executes the program’s bytecodes, thus performing the actions specified by the program.
In early Java versions, the JVM was simply an interpreter for Java bytecodes. This caused most Java programs to execute slowly, because the JVM would interpret and execute one bytecode at a time.
Some modern computer architectures can execute several instructions in parallel.

62. What do we do with it? Editing Compiling Running/Executing
Use any text editor you like (not a word processor!); save as Welcome.java
Compiling
From a DOS or UNIX command line, type
> javac Welcome.java
This should produce the file Welcome.class
Running/Executing
Again from the command prompt, type
> java Welcome

63. Note That Java programs actually go through two compilation phases—
one in which source code is translated into bytecodes (for portability across JVMs on different computer platforms) and
a second in which, during execution, the bytecodes are translated into machine language for the actual computer on which the program executes.
Problems That May Occur at Execution Time : divide by zero

64. Test your self What will be the out put of the following code:-
public class FormattingExample {
public static void main (String [] args)
System.out.print("lol\tz\n");
System.out.println("hello\rworld");
System.out.println("\"Geek\" talk slash (\\) com"); }

65. solution The output will be Lol z hello world
"Geek" talk slash (\) com

66. Questions (your turn)
1-The programs that translate high-level language programs into machine language are called ____________.
2-The command _______from the JDK executes a Java application.
3-The command ______from the JDK compiles a Java program.
4-A Java program file must end with the file extension______.
5-When a Java program is compiled, the file produced by the compiler ends with the file extension________.
6-The file produced by the Java compiler contains _____that are executed by the Java Virtual Machine.

67. Your turn …. Cont. 12- What is the out put of the following code:
class Display {
/* The Display Program
Illustrates a simple program displaying
a message. */
public static void main (String [ ] args) {
System.out.print( “Now is autumn " );
System.out.println( “weather is not stable" );
System.out.print( “sometimes hot " );
System.out.println( “sometimes cold" ); }

68. Answers 1- compilers. 2- java (file name). 3- javac (file name).
5- (file name).class.
6- bytecodes.
12- Now is autumn weather is not stable
sometimes hot sometimes called

69. Self study program
Design a program to output the following table on the screen. Not you must use the escape sequence.
Person height shoe size
===========================
Ahmed m 38
Ali m 43

70. solution
public static void main(String[] args) { System.out.println("person\t heiht\t size"); System.out.println("======================"); System.out.println("Ahmed\t1.7m\t38"); System.out.println("Ali\t2m\t43"); }

71. Agenda • Introduction - Programming Languages • First Program
• Output
• Directives
• Comments
• variables & identifiers
Integer Variables
• Input with scanner
• Variable Names
• Arithmetic Expressions
• The arithmetic assignment operators

72. Variables & Identifiers
programming is not limited only to printing simple texts on the screen. In order to go a little further on and to become able to write programs that perform useful tasks that really save us work we need to introduce the concept of variable.
we can define a variable as a portion of memory to store a determined value.
Each variable needs an identifier that distinguishes it from the others
a = 5; b = 2; a = a + 1; result = a - b;
Please read

73. Variable Names=identifier
The names given to variables are called identifiers.
What are the rules for writing identifiers?
You can use upper- and lowercase letters, and the digits from 1 to 9.
You can also use the underscore _.
The first character must be a letter or underscore.
Keywords is avoided.
Identifiers can be as long as you like, but most compilers will only recognize the first few hundred characters.
java is case sensitive: The compiler distinguishes between upper- and lowercase letters, so Var is not the same as var or VAR. 73

74. keyword A keyword is a predefined word with a special meaning.
int, class, if, and while are examples of keywords.
A complete list of keywords can be found in Appendix B, page 886, book “object oriented programming in C++”.
Note:
Declarations of variables can be placed almost anywhere in a program, but they must appear before their corresponding variables are used in the program. 74

75. Java Keywords abstract boolean break byte case catch char class const
continue
default do
double
else
extends
final
finally
float
for
goto if
implements
import
instanceof
int
interface
long
native
new
package
private
protected
public
return
short
static
super
switch
synchronized
this
throw
throws
transient
try
void
volatile
while

76. Declaring Variables: Syntax
Format:
<type of information> <name of variable>;
Example:
char a;
Variables can be initialized (set to a starting value) as they’re declared:
char myFirstInitial = ‘j’;
int age = 30;

77. Some Built-In Types Of Variables In Java
Description
byte
8 bit signed integer
short
16 but signed integer
int
32 bit signed integer
long
64 bit signed integer
float
32 bit signed real number
double
64 bit signed real number
char
16 bit Unicode character (ASCII and beyond)
boolean
1 bit true or false value
String
A sequence of characters between double quotes ("")

78. Location Of Variable Declarations
public class <name of class> {
public static void main (String[] args)
// Local variable declarations occur here
<< Program statements >>
: : }

79. Style Hint: Initializing Variables
Always initialize your variables prior to using them!
Do this whether it is syntactically required or not.
Example how not to approach:
public class OutputExample1 {
public static void main (String [] args)
int num;
System.out.print(num); }
OutputExample1.java:7: error: variable num might not have been initialized
System.out.print(num); ^

80. Java Constants
Reminder: constants are like variables in that they have a name and store a certain type of information but unlike variables they CANNOT change.
Format:
final <constant type> <CONSTANT NAME> = <value>;
Example:
final int SIZE = 100;

81. Location Of Constant Declarations
public class <name of class> {
public static void main (String[] args)
// Local constant declarations occur here (more later)
// Local variable declarations
< Program statements >>
: : }

82. Why Use Constants?
They make your program easier to read and understand
populationChange = ( – ) * currentPopulation;
Vs.
final float BIRTH_RATE = 17.58;
final float MORTALITY_RATE = ;
int currentPopulation = ;
populationChange = (BIRTH_RATE - MORTALITY_RATE) * currentPopulation;

83. Variables, cont. int -- integer type: range is system dependent
usually 32-bits -- +/- 2,147,483,648
16-bits on older systems -- +/- 32,768
float -- floating point number
char -- a single character
string -- more than an array of characters (a class)
we’ll look at these in more detail later..

84. Common Java Operators / Operator Precedence
Precedence level
Operator
Description
Associativity 1
expression++
expression--
Post-increment
Post-decrement
Right to left 2
++expression
--expression + - ! ~
(type)
Pre-increment
Pre-decrement
Unary plus
Unary minus
Logical negation
Bitwise complement
Cast

85. Common Java Operators / Operator Precedence
Precedence level
Operator
Description
Associativity 3 * / %
Multiplication
Division
Remainder/modulus
Left to right 4 + -
Addition or String concatenation
Subtraction 5
<<
>>
Left bitwise shift
Right bitwise shift

86. Common Java Operators / Operator Precedence
Precedence level
Operator
Description
Associativity 6
<
<=
>
>=
Less than
Less than, equal to
Greater than
Greater than, equal to
Left to right 7
= = !=
Equal to
Not equal to 8
&
Bitwise AND 9 ^
Bitwise exclusive OR

87. Common Java Operators / Operator Precedence
Precedence level
Operator
Description
Associativity 10 |
Bitwise OR
Left to right 11
&&
Logical AND 12 ||
Logical OR

88. Common Java Operators / Operator Precedence
Precedence level
Operator
Description
Associativity 13 = += -= *= /= %=
&= ^= |=
<<=
>>=
Assignment
Add, assignment
Subtract, assignment
Multiply, assignment
Division, assignment
Remainder, assignment
Bitwise AND, assignment
Bitwise XOR, assignment
Bitwise OR, assignment
Left shift, assignment
Right shift, assignment
Right to left

89. Example

90. Arithmetic Operators, cont.
There is no arithmetic operator for exponentiation in Java, so x2 is represented as x*x.

91. The arithmetic assignment operators
public static void main(String[ ] args) {
int j = 0,k = 5;
k = k - 5; }
The same variable may appear on both sides of an assignment operator
on the right hand side of the assignment operator, the variable in question represents its value prior to the execution of this statement.
on the left hand side of the assignment operator, the variable receives a new value which is the result of the evaluation on the right hand side.
In our example above, k ends up being “0”.

92. The arithmetic assignment operators, cont.
public static void main(String[] args)
{ int j = 0,k = 5;
k -= 5; // really like k = k - 5; }
When performing any other operation on a variable and stuffing the value back into the same variable, use a shortcut (like +=, -=, *=, %=)

93. The arithmetic assignment operators, cont.

94. Post/Pre Operators The name of the online example is: Order1.java
public class Order1 {
public static void main (String [] args)
int num = 5;
System.out.println(num);
num++;
++num;
System.out.println(++num);
System.out.println(num++); }
5,6,7,8,8

95. Post/Pre Operators (2) The name of the online example is: Order2.java
public class Order2 {
public static void main (String [] args)
int num1;
int num2;
num1 = 5;
num2 = ++num1 * num1++;
System.out.println("num1=" + num1);
System.out.println("num2=" + num2); }
7,36

96. Unary Operator/Order/Associativity
The name of the online example: Unary_Order3.java
public class Unary_Order3.java {
public static void main (String [] args)
int num = 5;
float fl;
System.out.println(num);
num = num * -num; }
5, -25. it islike - *(5,5)

97. Accessing Pre-Created Java Libraries
It’s accomplished by placing an ‘import’ of the appropriate library at the top of your program.
Syntax:
import <Full library name>;
Example:
import java.util.Scanner;

98. Getting Text Input
You can use the pre-written methods (functions) in the Scanner class.
General structure:
import java.util.Scanner;
main (String [] args) {
Scanner <name of scanner> = new Scanner (System.in);
<variable> = <name of scanner> .<method> (); }
Creating a scanner object (something that can scan user input)
Using the capability of the scanner object (actually getting user input)

99. Getting Text Input (2) The name of the online example: MyInput.java
import java.util.Scanner;
public class MyInput {
public static void main (String [] args)
String str1;
int num1;
Scanner input = new Scanner (System.in);
System.out.print ("Type in an integer: ");
num1 = in.nextInt ();
System.out.print ("Type in a line: ");
in.nextLine ();
str1 = input.nextLine ();
System.out.println ("num1:" +num1 +"\t str1:" + str1); }

100. Useful Methods Of Class Scanner1
nextInt ()
nextLong ()
nextFloat ()
nextDouble ()
nextLine ();

101. Reading A Single Character
Text menu driven programs may require this capability.
Example:
GAME OPTIONS
(a)dd a new player
(l)oad a saved game
(s)ave game
(q)uit game
There’s different ways of handling this problem but one approach is to extract the first character from the string.
Partial example:
String s = "boo“;
System.out.println(s.charAt(0));

102. Reading A Single Character
Name of the (more complete example): MyInputChar.java
import java.util.Scanner;
public class MyInputChar {
public static void main (String [] args)
final int FIRST = 0;
String selection;
Scanner input = new Scanner (System.in);
System.out.println("GAME OPTIONS");
System.out.println("(a)dd a new player");
System.out.println("(l)oad a saved game");
System.out.println("(s)ave game");
System.out.println("(q)uit game");
System.out.print("Enter your selection: ");

103. Reading A Single Character (2)
selection = in.nextLine ();
System.out.println ("Selection: " + selection.charAt(FIRST)); }

104. The best way to learn a programming language is to try writing programs and test them on a computer

105. Your Turn 1. Dividing a program into functions
a. is the key to object-oriented programming.
b. makes the program easier to conceptualize.
c. may reduce the size of the program.
d. makes the program run faster.
2. A function name must be followed by ________.
3. A function body is delimited by ________.
4. Why is the main() function special?
5. A C++ instruction that tells the computer to do something is called a ________.

106. Your Turn, cont.
9. True or false: A variable of type char can hold the value 301.
10. What kind of program elements are the following?
a. 12
b. ‘a’ c
d. JungleJim
e. JungleJim()

107. Your Turn, cont. 11. Write statements that display on the screen
a. the character ‘x’
b. the name Jim
c. the number 509
12. True or false: In an assignment statement, the value on the left of the equal sign is always equal to the value on the right.
15. Write a statement that gets a numerical value from the keyboard and places it in the variable temp.

108. Your Turn, cont. 19. The expression 11%3 evaluates to ________.
21. Write a statement that uses an arithmetic assignment operator to increase the value of the variable temp by 23. Write the same statement without the arithmetic assignment operator.
22. write a program in order to ask the user about the number of programming language he had before, the out the statement “enjoy the book” to the screen?

109. 23- Write a program which asks the user to insert two integer values then out put on the screen
The incrementing by one to each intergers.
The multiplication of both;
The adding of both numbers.

110. Answers 1- b,c. 2-parentheses 3- braces { }
4- It’s the first function executed when the program starts
5- statement
9- false
10- a. integer constant
b. character constant
c. floating-point constant
d. variable name or identifier
e. function name
11.
a. cout << ‘x’;
b. cout << “Jim”;
c. cout << 509;
12- false; they’re not equal until the statement is executed
15- cin >> temp;
19- 2
21-
temp += 23;
temp = temp + 23;

111. cout<<"enter the first number\n"; cin>>n;
22- #include <iostream>
using namespace std;
int main( ) {
int numberOfLanguages;
cout << "Hello reader.\n“ << "Welcome to C++.\n";
cout << "How many programming languages have you used? ";
cin >> numberOfLanguages;
cout << "Enjoy the book.\n";
return 0; }
22. #include <iostream>
int main(){
int n,m;
cout<<"enter the first number\n";
cin>>n;
cout<<"enter the second number\n";
cin>>m;
n++; m++;
cout<<"the first number after increment is "<<n<<endl;
cout<<"the second number after increment is "<<m << endl;
n--; m--;
cout<< "the multiplication of the two integers are"<<m*n<<endl;
cout<< "the addition of the two integers are"<<m+n<<endl; }

112. Lecture 3 Agenda Text book “absolute C++” Chapter1:C++ basics cont.
Variable types
Char, string, float, const, boolean.
Type conversion
Math operations
Chapter 2: flow of control
Boolean expression.
Branching mechanisms.
Loops.
Introduction to file input.

113. Character variable // charvars.cpp // demonstrates character variables
#include <iostream> //for cout, etc.
using namespace std;
int main() {
char charvar1='A'; //define char variable as character
char charvar2='\t'; //define char variable as tab
cout << charvar1; //display character
cout << charvar2; //display character
cout << "\n"; //display newline character
return 0; }

114. Character variable : Escape Sequences
\ xdd Hexadecimal notation
Sometimes you need to represent a character constant that doesn’t appear on the keyboard, such as the graphics characters above ASCII code 127.
To do this, you can use the “\xdd” representation,
where each d stands for a hexadecimal digit.
cout << “\xE0”; //display α
cout << “\xB2”; //display solid rectangle

115. ASCII Table

116. String variable
In order to use string variable type, we have to use special library called “String”.

117. Cin>> with string variable type

118. String variable #include <iostream>
#include <String> //using string variable
using namespace std;
int main() {
string strname; // identify a string variable
cout<<" enter your name"<< endl;
cin>>strname;
cout<<"you typed the name"<<strname<<endl;
return 0; }
If the user write more thane one name part strname variable will use only the first name.

119. Floating Point Types
represent numbers with a decimal place—like , , and –10.2.
There are three kinds of floating-point variables in C++:
type float,
type double,
and type long double
float PI = F; //the F specifies that it’s type float
You can also write floating-point constants using exponential notation.
Exponential notation is a way of writing large numbers without having to write out a lot of zeros.
For example:
1,000,000,000 can be written as 1.0E9 in exponential notation.
E–5 is equivalent to in decimal notation

120. The const Qualifier
120120
The keyword const (for constant) precedes the data type of a variable.
It specifies that the value of a variable will not change throughout the program.
Any attempt to alter the value of a variable defined with this qualifier will elicit an error message from the compiler.
const float PI = F; //type const float

121. Example: circarea.cpp
121121
// circarea.cpp // demonstrates floating point variables #include <iostream> //for cout, etc. using namespace std; int main() { float rad; //variable of type float const float PI = F; //type const float cout << "Enter radius of circle: "; //prompt cin >> rad; //get radius float area = PI * rad * rad; //find area cout << "Area is " << area << endl; //display answer return 0; }

122. Type bool
122122
Variables of type bool can have only two possible values: true and false.
type bool is most commonly used to hold the results of comparisons.

123. Basic C++ Variable Types
123123

124. Type Conversion
124124
C++ treats expressions involving several different data types.
int main() {
int count = 7;
float avgWeight = 155.5F;
double totalWeight = count * avgWeight;
cout << “totalWeight=” << totalWeight << endl;
return 0; }

125. Type Conversion, cont.
125125
When two operands of different types are encountered in the same expression, the lower-type variable is converted to the type of the higher-type variable.

126. Type Conversion, cont. int count = 7; float avgWeight = 155.5F;
126126
int count = 7;
float avgWeight = 155.5F;
double totalWeight = count * avgWeight;
the int value of count is converted to type float and stored in a temporary variable before being multiplied by the float variable avgWeight.
The result (still of type float) is then converted to double so that it can be assigned to the double variable totalWeight.

127. Type Conversion, cont.
127127

128. Type Conversion, cont. Casts
128128
Cast convert a value from one type to another.
CharVar = static_cast<char>(nIntVar);
Example:
cout<< static_cast<int>('A'); // print ‘A’ as integer , 65
cout<< static_cast<char>(65); // print 65 as ‘A’

129. Increment and Decrement Operators, cont.

130. Increment and Decrement Operators, cont.
When you increment (++) or decrement (--) a variable in a statement by itself, the pre-increment and post-increment forms have the same effect, and the pre-decrement and post-decrement forms have the same effect.
X++;
++X;
It’s only when a variable appears in the context of a larger expression that pre-incrementing the variable and post-incrementing the variable have different effects (and similarly for pre-decrementing and post-decrementing).
The Next slide shows the precedence and associatively of the operators introduced to this point.
130

131. Increment and Decrement Operators, cont
Increment and Decrement Operators, cont. The precedence of the operators
131131

132. Increment and Decrement Operators, cont.
132132
totalWeight = avgWeight * ++count;
count is incremented first and then multiply with avgWeight
totalWeight = avgWeight * count ++;
the multiplication would have been performed first, then count would have been incremented.

133. Increment and Decrement Operators, cont.
133133

134. Math Library Function
134134
// sqrt.cpp // demonstrates sqrt() library function #include <iostream> //for cout, etc. #include <math.h> //for sqrt() using namespace std; int main() { double number, answer; //sqrt() requires type double cout << “Enter a number: “; cin >> number; //get the number answer = sqrt(number); //find square root cout << “Square root is “ << answer << endl; //display it return 0; } Enter a number: 1000 Square root is

135. Math Library Function, cont.
135135

136. Math Library Function, cont.
136136

137. Outlines Chapter 2 – flow of control Boolean expressions
137137
Chapter 2 – flow of control
Boolean expressions
Branching mechanisms
Loops
Decisions

138. Control Structures
138138
Normally, statements in a program execute one after the other in the order in which they’re written.
Called sequential execution.
Various C++ statements enable you to specify that the next statement to execute may be other than the next one in sequence.
Called transfer of control.
All programs could be written in terms of only three control structures
the sequence structure
the selection structure and
the repetition structure

139. Boolean expressions
139139
Most branching statements are controlled by Boolean expressions.
A Boolean expression is any expression that is either true or false.
The simplest form for a Boolean expression consists of two expressions, such as numbers or variables, which are compared with one of the comparison operators as shown.

140. Building Boolean Expressions
One can combine two comparisons in order to build a Boolean expression.
Ex (2 < x) && (x < 7).
It means that the expression is true if x is greater than 2 and x is less than 7.
When two comparisons are connected using an && , the entire expression is true, if both of the comparisons are true; otherwise, the entire expression is false.
Ex. (y < 0)||(y < 12)
When two comparisons are connected using a || , the entire expression is true provided that one or both of the comparisons are true; otherwise, the entire expression is false.

141. Evaluating Boolean Expressions
141141
#include <iostream> //for cout, etc.
using namespace std;
int main()
{ int y;
bool Opor, Opand;
cout<<"enter number";
cin>>y;
Opor=(y<7)||(y>2);
cout<<"the result of the or operator is\n"<<Opor<<endl;
Opand=Opor=(y<7)&&(y>2);
cout<<"the result of the and operator is \n"<<Opand;
return 0;}
C++ compiler considers that a true expression has the value 1, while a false expression has the value 0.

142. Evaluating Boolean Expressions cont.
142142

143. Precedence Rules
Boolean expressions (and arithmetic expressions) need not be fully parenthesized.
If you omit parentheses, the default precedence will be used.
143143
High precedence
low precedence

144. Some expressions that use Boolean expression
144144
int x= 44; //assignment statement
int y = 12; //assignment statement
bool b1= (x== y); //false
bool b2=(y <= 12); //true
bool b3=(x> y); //true
bool b4=(x>= 44); //true
bool b5=(y != 12); // false
bool b6=(7 < y); //true
bool b7=(0); //false (by definition)
bool b8=(44); //true (since it’s not 0)
Although C++ generates a 1 to indicate true, it assumes that any value other than 0 (such as –7 or 44) is true; only 0 is false.