CECS 121 EXAM 1

/* C Programming for the Absolute Beginner */ // by Michael Vine #include main() { printf(“\nC you later\n”); system(“pause”); }

Serve to control program execution and functionality. Must end with a semicolon(;) with the exception of:  Comments: /* */  Preprocessor Directives: #include or #define  Begin and end program identifiers: { }  Function definition beginnings: main()

 Functions allow you to group program statements under one name  C is case-sensitive so main(), MAIN(), and Main() are all different  The main function is special because the values it returns are returned to the operating system  Most main functions in this course do not take or pass information to the operating system

 Definition: Escape sequences are specially sequenced characters used to format output  \”  Ex: printf(“ \ “This is quoted text \ “ “)  \’  Ex: printf(“ \n A single quote looks like \’ \n”);  \* *\ Comment Block

 #include  Using a directive to include a header file  stdio.h = standard input output header file  stdlib.h = ‘system’ commands

 A computer’s long-term memory is called nonvolatile memory and is generally associated with mass storage devices, such as hard drives.  A computer’s short term memory is called volatile memory. It loses is data when power is removed from the computer

To declare a constant (read only) value: const int x = 20; const float PI = 3.14;

TYPESIZEVALUES bool1 bytetrue (1) or false (0) char1 byte‘a’ to‘z’, ‘A’ to ‘Z’, ‘0’ to ‘9’, space, tab, and so on int4 bytes-2,147,483,648 to 2,147,483,647 short2 bytes-32,768 to 32,767 long4 bytes-2,147,483,648 to 2,147,483,647 float4 bytes+ - (1.2 x 10^-38 to 3.4 x 10^38) double8 bytes+- (2.3 x 10^-308 to -1.7 x 10^308)

 Can you explain what the code is doing?

 Character - %c  Integer - %d  Float (decimal)- %f  String - %s  Printf Format Tags: %[flags][width][.precision][length]specifier %[.precision]specifer -> %.2f

 int main() { printf (“%c %c \n", 'a', 65); printf (" %10d \n", 1977); printf ("%010d \n", 1977); printf ("floats: %4.2f \n", ); printf ("%s \n", "A string"); printf(“%f \n”, 55.55); return 0; } }

printf (“%c %c \n", 'a', 65); aA printf ("%d %ld\n", 1977, L); printf (" %10d \n", 1977); 1977 printf ("%010d \n", 1977); printf ("floats: %4.2f \n", ); 3.14 printf ("%s \n", "A string"); A string  Can you create a tabular data using printf?

 Syntax scanf(“conversion specifier”, variable);

#include main() { int iOperand1 = 0; int iOperand2 = 0; printf(“\n Enter first operand: “); scanf(“%d”, &iOperand1); printf(“\n Enter second operand: “); scanf(“%d”, &iOperand2); printf(“The result is %d \n”, 24/(iOperand1 * iOperand2)+6/3); }

#include main() { int x = 4; int y = 9; int result1, result2; result1 = y/x; result2 = y%x; printf(“The result is %d.%d \n”, result1, 25*result2); }

Do you know the answers to these?  A. !( 1 || 0 )  B. !( 1 || 1 && 0 )  C. !( ( 1 || 0 ) && 0 )

 A. !( 1 || 0 ) ANSWER: 0  B. !( 1 || 1 && 0 ) ANSWER: 0 (AND is evaluated before OR)  C. !( ( 1 || 0 ) && 0 ) ANSWER: 1 (Parenthesis are useful)

 Can you write code that will ask a user to enter a number 1, 2, or 3 and print out the following:

#include int main() { int a; printf (“Enter one of the following: %d, %d, or %d\n”, 1, 2, 3); scanf(“%d”, &a); if(a==1|| a==2|| a ==3) { if(a==1){ printf(“\n %d is the loneliest number \n“, 1); } if(a==2){ printf(“\n%d is better than %d \n”,2,1); } if(a==3){ printf(“\n%d \’ s a crowd \n”,3); } else printf(“Sorry, you entered an invalid value\n”); return 0; }

 while ( condition ) { Code to execute while the condition is true }  Quiz: Can you write a program that prints x while x increments from 0 to 10?

x++;Tells the function to use the current value of x and increment it by 1. ++x;Increment the value of x by 1 and use the new value for calculations. x--; Tells the function to use the current value of x and decrease its value by 1. --x; Decrease the value of x by 1 and use the new value for calculations. x=0; printf(“The Value of x is: %d”, x++); printf(“\n The Value of x is: %d”,++x); Would results in:The Value of x is: 0 The Value of x is: 2

 Often used when the # of iterations is already known.  Contains 3 separate expressions: 1. Variable initialization 2. Conditional expression 3. Increment/Decrement Try writing a program with a for loop that counts down from 10 seconds.

#include main() { int x=0; for(x=10; x>=0; x--) { printf("%d \n", x); } system("pause"); }

 break; Used to exit a loop. Once this statement is executed the program will execute the statement immediately following the end of the loop.  continue; Used to manipulate program flow in a loop. When executed, any remaining statements in the loop will be skipped and the next iteration of the loop will begin

 Function Prototype Syntax return-type function_name ( arg_type arg1,..., arg_type argN)  Function Prototypes tell you the data type returned by the function, the data type of parameters, how many parameters, and the order of parameters  Function definitions implement the function prototype  Where are function prototypes located in the program?  Where do you find function definitions?

 Where are function prototypes located in the program?  Answer: before the Main(){} Function!  Function Definitions are self contained outside of the Main(){} function

#include int mult ( int, int ); int main() { int x; int y; printf( "Please input two numbers to be multiplied: " ); scanf( "%d", &x ); scanf( "%d", &y ); printf( "The product of your two numbers is %d\n", mult( x, y ) ); getchar(); } int mult (int a, int b) { return a * b; }

#include Void printReportHeader(); main() { printReportHeader; } void printReportHeader() { printf(“\n Column1\tColumn2\tColumn3\tColumn4 \n”); }

#include void printNumbers(); int iNumber; main() { int x; for(x=0, x<10,x++){ printf(“\n Enter a number:”); scanf(“%d”, &iNumber); printNumbers(); } void printNumbers() { printf(“\n Your number is: %d \n”, iNumber); }

 Variable scope defines the life time of a variable  Local Scope: defined within functions and loses scope after function is finished. Can reuse in other functions (ex. p.123)  Global Scope: defined outside of functions and can be accessed by multiple functions