1. introduction to computer programs
Chapter 1
introduction to computer programs

2. Chapter Outline A Brief History of Programming Language
Introduction to Programming
What is a computer program and importance of computer programming
Importance of good programs.
Relationship between compilers, interpreters, assemblers and programs
C++ program structure
Program Development Life Cycle
Problem solving phases; problem definition, algorithm design and implementation
Analysis, design, coding, maintenance

3. Chapter Outcome At the end of this class, student should be able to:
Understand the concept and importance of program and programming
Differentiate between compiler, program, interpreter and assembler
Apply the steps in program development life cycle.

4. A Brief History Of Programming Language
Programming Language is an artificial and formal language that has a limited vocabulary consisting of a set of keywords for making up instructions and a set of precise grammar rules.
Example: C, C++, Java, COBOL

5. A Brief History Of Programming Language
The Language of Computer
Digital signals are sequences of 0s and 1s
Machine language: language of a computer
Binary digit (bit) The digit 0 or 1
Binary code  A sequence of 0s and 1s
Byte  A sequence of eight bits

6. Types of Programming Language
A Brief History Of Programming Language
Types of Programming Language
Low-level Language
Machine Language
Early computers were programmed in machine language
Assembly Language
Assembly language instruction are mnemonic (use code, easier to remember)
Assembler: translates a program written in assembly language into machine language
High-level Language
Languages that are machine independent.
Instructions are quite English-like
Single instruction can be written to correspond to many operations at the machine level.
Include Basic, FORTRAN, COBOL, Pascal, C++, C, and Java
Compiler: translates a program written in a high-level language machine language
The equation BMI = weight (kg) / (height (m) x height (m))
can be written in C++ as: BMI = weight/pow(height,2);

7. Example of Programming Language
A Brief History Of Programming Language
Example of Programming Language
machine language:
BMI = weight/pow(height,2);
// Load
// Multiply
// Store
assembler
compiler
ASSEMBLY LANGUAGE
LOAD
STOR
MULT
ADD
SUB
MACHINE LANGUAGE
100100
100010
100110
100101
100011
High Level Language
BMI = weight/pow(height,2);

8. Introduction To Programming
What is Computer?
A device capable of performing computations and making logical decisions at speed faster than human being.
An electronic machine, operating under the control of instructions stored in its own memory

9. Accepting data from a user
Basic Operation of a Computer
Accepting data from a user
Manipulating data
Producing results
INPUT
PROCESS
OUTPUT
STORAGE
Storing results
** These operations are under the control of instructions stored in the computer’s memory

10. Component of a Computer
HARDWARE
SOFTWARE
COMPUTER
The series of
instructions that tells the
computer hardware how
to perform tasks
The electric, electronic
and mechanical
equipment that makes up
a computer

11. What is a program?
A program is a set of instructions that tells the computer how to solve a problem or perform a task.
A program is like a recipe. It contains a list of ingredients (variables) and a list of directions (statements) that tell the computer what to do with the variables.
A computer program is a set of detailed directions telling the computer exactly what to do, one step at a time.
A program can be as short as one line of code, or as long as several millions lines of code.

12. What is a program?
Computer process data under the control of sets of instructions called computer program.
Computer programs guide the computer through orderly sets of actions specified by computer programmers.

13. What is a programming?
A programming is designing and writing a computer program.
The programmer must decide what the program needs to do, develop the logic of how to do it, and write instructions for the computer in a programming language that the computer can translate into its own language and execute.

14. The Importance Of Good Program
Some people consider Computer Programming as an Art which must follow certain standards in order to promote program clarity, readability, and comprehension so as to produce programs that are easier to read, test, debug, modify, and maintain.
Standards that have been emphasize by most of the programmers are:
Names for variables, types and functions.
Indent style and spacing.

15. The Importance Of Good Program
Names for variables, types and functions.
Choosing an appropriate variable names is seen as the basis for good style programming
The following are some rules that can be used when naming variables, types and functions:
Function names will start with a lower case letter.
Example:
double averageMark (double, double);
Variable names start with a lower case letter and the length must not be more than 40 characters.
Constant names can be all capital letters.
Example: const int MAX_SIZE = 10.

16. The Importance Of Good Program
Indent style and spacing.
In order to improve its readability in programming, indentation is used to format program source code.
Adding spaces in between sentence makes your program much more readable.
A new level of indentation should be used at every level of statement nesting in your program.
The minimum number of spaces at each indentation should be at least 3, and many programmers use a tab mark (typically 8 spaces).

17. The Importance Of Good Program
Indent style and spacing.
Comparison
Style 1
if (marks > 50) {
return PASS; }
else
return FAIL;
Style 2
if(marks>50{return PASS;} else
{return FAIL;}
Style 1 is much easier to read because they are indented well, and logical blocks of code are grouped and displayed together more clearly.

18. Relationship Between Compilers, Interpreters, Assemblers and Program
All programs have to be translated into machine code before the computer can actually run them. 
Programs written in high-level languages are translated into machine language by a compiler or interpreter.

19. Relationship Between Compilers, Interpreters, Assemblers and Program
a computer program that translates and executes a program written in a high-level language.
translates the source program, instruction by instruction, each time that program is run.
An interpreter translates program statements one at a time.
Interpreters are helpful during the debugging stage, but are slower during execution of the finished program.

20. Relationship Between Compilers, Interpreters, Assemblers and Program
a computer program that translates programs written in a high-level language into machine code.
translates each high-level instruction into several machine-code instructions all at once time.
Compiler runs much faster than an interpreted program.

21. Relationship Between Compilers, Interpreters, Assemblers and Program
Consists of little more than a table look up routine, where each word of the source language (assembly language) is looked up in a table for its numerical equivalent, which is then output as part of the target language program.
Assembly language generally gives the programmer precise and direct access to every capability of the computer hardware.

22. C++ Program Structure
How to write a complete program that consist certain
element:
Begin the program with comments for documentation
Include header files, if any are used in the program
Declare variables and constants, if any
Write the definition of the function main

23. Elements Of Computer Program
General form of a C++ Program
// Introductory comments // file name, programmer, when written or modified // what program does #include <iostream.h> void main() { constant declarations ; variable declarations;
executable statements ; }

24. Elements Of Computer Program
Example of C++ program:
#include <iostream.h>  compiler directive/header file
void main( ) main function {
//display greeting message  comment
cout<<”Welcome to CSC 128 class”;  statement }
OUTPUT
Welcome to CSC 128 class
braces

25. Example of C++ program:
Elements Of Computer Program
Comments
Preprocessor directives
Function
Begin block /*
File Name : bmi.cpp
Programmer : Alif
Matrix No :
Topic : Exercise 1
Program purpose : This program to calculate bmi for a user.
Date : 20 October 2013 */
#include <iostream.h>
#include <math.h>
void main() {
double weight, height,bmi;
cout << "Enter weight in kg: ";
cin >> weight;
cout << "Enter height in meter: ";
cin >> height;
bmi = weight /pow(height,2);
cout << "The BMI is : "<<bmi<<endl; }
Function Body
End block
Example of C++ program:

26. Elements Of Computer Program

27. Comments Important part of a program's documentation.
It is used to explain the purpose of a program.
Explain the parts of program and keep note regarding changes to the source code.
Describe about the reason of the program and understand the program more clearly.
Increased the user understanding of the program.
Store the names of programmers for future reference.
Used to make program documentation.

28. Comments Can be used in 2 ways: Using /* */ symbol
Used for one or more than one line of comments in group
Example:
/* This is the example of comment in C++ program.This is the second line */

29. Comments 2. Using // symbol Used only for one line Example:
// This is example of comments
// This is the second line

30. Preprocessor Directive
A line of code that begins with the # symbol.  
Are processed by preprocessor (which is usually bundled into the compiler) before compilation.
Are not executable code lines but instructions to the compiler.
Each header file stores functions that are related to a particular application.
The directive #include <iostream.h> tells the preprocessor to include the contents of the file iostream.h, which includes input-output operations (such as printing to the screen). 

31. Function Main Function
Every C++ program contains one or more functions, one of which must be named main.
Every C++ program has a main function.
A function is a block of code that carries out a specific task.
The word main is followed in the code by a pair of parentheses ( ).

32. Function
Braces
Right after these parentheses we can find the body of the main function enclosed in braces { }.
What is contained within these braces is what the function does when it is executed.
Braces used to mark the beginning and end of blocks of code.
The open braces ({ ) are place in the beginning of code after the main functions and close braces ( }) are used to show closing of code.
The code after the ( }) will not be read/evaluate by compiler

33. Function
Statement
A function consists of a sequence of statements that perform the work of the function.
It consists of instructions or command which make the program work.
Each statement in C++ ends with a semicolon (;).
There are 3 type of statement :
Input statement- cin>>statement;
Output statement-cout<<“statement”;
Operation statement-mathematical operation

35. Problem Solving Phases
To be a good programmer, you must be a good problem solver.
To be a good problem solver, you must understand a problem in a methodical way, from initial inspection and definition to final solution.

36. Problem Solving Phases
Program Development Life Cycle
Creating new program is called program development
The process associated with creating successful applications programs is called the Program Development Life Cycle (PDLC).
There are 5 steps to Program Development Life Cycle:
Analysis
Design
Implementation/ Coding
Testing/ Debugging
Program Maintenance

37. Problem Solving Phases Phase 1: Analysis
Done by reviewing the program specifications.
Eliminate ambiguities in the problem statement.
Other criteria must be identified especially the data that will be used as input, process involve and output that will be produced.
Indicating what the new system should do.
In this step, the objectives, outputs, inputs, and processing requirements are determined.
The program objectives are the problems that you are trying to solve.

38. Example of Problem Solving Exercise
Problem Solving Phases
Phase 1: Analysis
Example of Problem Solving Exercise
Write a program to calculate the bmi of a user
Objective :
- To calculate the bmi of a user
Output :
- bmi
Input :
- weight , height
Process :
- Declare  double bmi, weight, height
- Calculate  bmi= weight/pow(height,2)

39. Problem Solving Phases Phase 2: Design
Develop a series of steps with a logical order which, when applied would produce the output of the problem.
Good program design is very important in order to make the development process run smoothly, as well as to make future revisions easier.
In program design step, a solution is created using structured programming techniques such as top-down approach and algorithm which consist of pseudocode and flowchart.

40. Problem Solving Phases Phase 2: Design
Algorithm

41. Problem Solving Phases Phase 2: Design
What is Algorithm?
A step-by-step problem solving process in which a solution is arrived at a finite amount of time.
A sequence of a finite number of steps arranged in a specific logical order which when executed will produce the solution for that problem.
An algorithm must satisfy some requirements which are:
Unambiguousness (clear)
Generality (unspecific)
Correctness
Finiteness (limitation)

42. Problem Solving Phases Phase 2: Design Algorithm
Pseudo code
Flowchart

43. Problem Solving Phases Phase 2: Design
Algorithm – Pseudocode
Is a semiformal, English like language with a limited vocabulary that can be used to design and describe algorithms.
Each pseudo code statement includes keywords that describe operations and some appropriate English like description of operands.
Each pseudo code statement should be written on a separate line.

44. Problem Solving Phases Phase 2: Design
Algorithm – Pseudocode
The statements that make up a sequence control structure should begin with unambiguous words such as compute, set and initialize.
For the selection control structure use an if-else statement.
For repetition control structure use the for /while /do..while statement and indent the loop body.
All words in a pseudo code statement must be unambiguous and as easy as possible for nonprogrammers to understand.

45. Problem Solving Phases Phase 2: Design
Algorithm – Pseudocode
Example: (Sequential Control Structure)
calculate the bmi of a user
BEGIN
DECLARE double bmi, weight, height
READ weight, height
CALCULATE bmi=weight/pow(height,2)
DISPLAY bmi

46. Problem Solving Phases Phase 2: Design
Algorithm – Pseudocode
Example: (Selection Control Structure)
Identify whether a number is a positive or negative number
BEGIN
DECLARE int num
GET num
IF (num>0)
DISPLAY positive number
ELSE
DISPLAY negative number
END

47. Problem Solving Phases Phase 2: Design
Algorithm – Pseudocode
Example: (Repetition Control Structure)
Get three numbers and find the total of the three numbers
BEGIN
DECLARE int num, n, total
INITIALIZE total=0, n=1
WHILE (n<=3)
GET num;
total=total+num;
n++;
DISPLAY total
END

48. Problem Solving Phases Phase 2: Design
Algorithm – Flowchart
A graphic presentation of the detailed logical sequence of steps needed to solve programming problems.
Uses geometric symbols and familiar relational operators to provide a graphic display of the sequence of steps involved in a program.
The steps in a flowchart follow each other in the same logical sequence as their corresponding program statements will follow in a program.
Different symbols are used to represent different actions, such as start/stop, decision, input/output, processing, and looping symbols.

49. Problem Solving Phases Phase 2: Design
Algorithm – Flowchart
Symbol
Name
Description
Flowline
To connect symbols and indicate the flow of logic
Terminal
Used to represent the beginning (Start) or the end (End) of a program
Input/Output
Used for input and output operations, such as reading and printing.
Processing
Used for arithmetic and data manipulation operations.
Decision
Used for any logic or comparisons operations.
This symbol has one entry and two exit paths.
The path chosen depend on whether the answer to question is “yes” or “no”
Connector
Used to join different flowlines
Offpage Connector
Used to indicate that the flowchart continues to next page

50. Problem Solving Phases Phase 2: Design
Algorithm – Flow Chart
Example:
Sequential Control Structure
Calculate the bmi of a user

51. Problem Solving Phases Phase 2: Design
Algorithm – Flow Chart
Example:
Selection Control Structure
Identify whether a number is a positive or negative number

52. Problem Solving Phases Phase 2: Design
Algorithm – Flow Chart
Example:
Repetition Control Structure
Get three numbers and find the total of the three numbers

53. Problem Solving Phases Phase 2: Design
Algorithm – Flow Chart
Example: Function
Calculate the area of a room by using 2 functions: getInput()and calculate()

54. Problem Solving Phases Phase 2: Design
Algorithm – Flow Chart
Example: using off page connector

55. Problem Solving Phases Phase 3: Implementation/Coding
The pseudo code or flow diagram will be converted to a program by using a certain programming language (eg.: BASIC, Java, C++).
Coding is the actual process of creating the program in a programming language.
The coded program is referred to as source code.
To be executed, the program is converted by the computer to object code using a special program (compiler or interpreter)

56. Problem Solving Phases Phase 4: Testing/Debugging
Check and verify for the correctness of the result.
Debugging is the process of making sure a program is free of errors, or “bugs.”
Preliminary debugging begins after the program has been entered into the computer system.
The process whereby we will correct the error and run the program successfully

57. Problem Solving Phases Phase 5: Maintenance
Virtually every program, if it is to last a long time, requires ongoing maintenance.
Process of updating software so that it continues to be useful.
A costly process, but can be used to extend the life of a program.

58. Question 1
Write a program to calculate pressure using the formula given.
Analysis
OUTPUT
INPUT
PROCESS

59. Declare double ALL variable GET/READ Patm , h , p , g
Pseudocode
Begin
Declare double ALL variable
GET/READ Patm , h , p , g
CALCULATE p= Patm + hpg
DISPLAY p
END

60. Flowchart

61. Question 1- Answer P Patm, h,p,g P = Patm + hpg
Write a program to calculate pressure using the formula given.
Analysis
OUTPUT
INPUT
PROCESS P
Patm, h,p,g
P = Patm + hpg 

62. DECLARE double P, Patm , Hpg GET Patm, Hpg CALCULATE P = Patm + Hpg
Pseudocode
BEGIN
DECLARE double P, Patm , Hpg 
GET Patm, Hpg
CALCULATE P = Patm + Hpg
DISPLAY P
END

63. Flowchart START DECLARE double P, Patm , Hpg CALCULATE P=Patm + Hpg
DISPLAY P
END
CALCULATE P=Patm + Hpg
GET Patm, Hpg

64. Question 2
Write the flowchart for the pseudocode given below:

65. CALCULATE area = side1 * side2
Answer : Flowchart
START
DECLARE
int side1, side2, area
DISPLAY area
END
CALCULATE area = side1 * side2
GET side1, side2

66. Question 3
Write pseudocode for the flowchart given below:

67. CALCULATE Pay = Hours * Rate DISPLAY Name, Pay END
Pseudocode : ANSWER
BEGIN
DECLARE char Name[50];
double Hours, Rate, Pay
INPUT Name, Hours, Rate
CALCULATE Pay = Hours * Rate
DISPLAY Name, Pay
END

68. Question 4 Draw a flowchart based on the pseudocode given below: BEGIN
DECLARE double b,h ,A
GET b,h
COMPUTE A=b*h
PRINT A,b,h
END
(Hint: A-Area of parallelogram, b-base,h-height)
Formula: A=b*h

69. Flowchart : Answer BEGIN END DECLARE double b, h, A GET b,h COMPUTE
A = b * h
PRINT A,b,h
DECLARE double b, h, A
BEGIN
END

70. Question 5
A retail store grants its customers a maximum amount of credit. Each customer’s available credit is his or her maximum amount of credit minus the amount of credit used. Write a pseudo code and flowchart algorithm for a program that asks for a customer’s maximum amount of credit and amount of credit used. The program should then display the customer’s available credit.
Answer:
Program Analysis / Specification
OUTPUT
INPUT
PROCESS
availableCredit
creditLimit , creditUsed
Available = limit - used

71. balance = maxAmount - amountUsed
Question 5 : Answer
A retail store grants its customers a maximum amount of credit. Each customer’s available credit is his or her maximum amount of credit minus the amount of credit used. Write a pseudo code and flowchart algorithm for a program that asks for a customer’s maximum amount of credit and amount of credit used. The program should then display the customer’s available credit.
Program Analysis / Specification
OUTPUT
INPUT
PROCESS
balance
maxAmount, amountUsed
balance = maxAmount - amountUsed

72. Pseudocode
BEGIN
DECLARE double balance, maxAmount, amountUsed
READ maxAmount,amountUsed
CALCULATE balance = maxAmount – amountUsed
DISPLAY balance
END

73. Flowchart BEGIN END DECLARE double balance, maxAmount, amountUsed
READ maxAmount, amountUsed
CALCULATE
balance = maxAmount - amountUsed
DISPLAY balance
DECLARE double balance, maxAmount, amountUsed
BEGIN
END