Control Constructs

Source Code from Notes

Example 1

/*Program to calculate absolute value of an integer*/

#include <stdio.h>

main()
{
        int     number;

        /*Enter number*/
        printf("Enter a number: ");
        scanf("%d",&number);

        /*test if negative*/
        if (number < 0)
                number = -number;

        /*output results*/
        printf("The absolute value is %d\n",number);
}

Example 2

/*Program to test if number is even or odd*/

#include <stdio.h>

main()
{
        int     number,remainder;

        printf("Enter a number: ");
        scanf("%d",&number);

        remainder = number % 2;

        if (remainder ==0)
                printf("The number is even\n");
        else
                printf("The number is odd\n");
}

Example 3

/*Program to illustrate the use of nested if statements*/

#include <stdio.h>

main()
{
        int number;

        printf("Enter a number between 1 and 99: ");
        scanf("%d",&number);

        if (number > 0 && number < 100 ) 
        {
                if (number < 10)
                        printf("One digit number\n");
                else
                        printf("Two digit number\n");
        }
        else
                printf("Number not in range\n");
}

Example 4

#include <stdio.h>

main()
{
        int number, n_digits = 0;

        printf("Enter a number: ");
        scanf("%d",&number);

	if (number >= 100)
        	n_digits = 3;
	else if (number >=10)
        	n_digits = 2;
	else if (number >=0)
        	n_digits = 1;
	else
        	printf("Value out of range\n");

	if (n_digits > 0)
		printf("The number has %d digits\n", n_digits);
}

Example 5

#include <stdio.h>

main()
{
        char    day;

        printf("Which day?");
        day = getchar();

        switch(day){
                case 's': printf("Weekend\n");
                          break;
                case 'm': printf("Week day\n");
                          break;
                case 't': printf("Week day\n");
                          break;
                case 'w': printf("Week day\n");
                          break;
                case 'f': printf("Week day\n");
                          break;
                default:  printf("Not a day\n");
        }
}

Example 6

#include <stdio.h>

main()
{
        char    day;

        printf("Which day?");
        day = getchar();

        switch(day){
                case 's': case 'S': printf("Weekend\n");
                          break;
                case 'm': case 'M': printf("Week day\n");
                          break;
                case 't': case 'T': printf("Week day\n");
                          break;
                case 'w': case 'W': printf("Week day\n");
                          break;
                case 'f': case 'F': printf("Week day\n");
                          break;

                default:  printf("Not a day\n");
        }
}

Example 7

#include <stdio.h>

main()
{
        int 	input_value;

        printf("Which day?");

        scanf("%d",&input_value);

        switch (input_value){
                case 1: printf("The day is Monday\n");
                        break;
                case 2: printf("The day is Tuesday\n");
                        break;
                case 3: printf("The day is Wednesday\n");
                        break;
                case 4: printf("The day is Thursday\n");
                        break;
                case 5: printf("The day is Friday\n");
                        break;
                case 6: printf("The day is Saturday\n");
                        break;
                case 7: printf("The day is Sunday\n");
                        break;
                default : printf("Invalid Input\n");
                        break;
        }
}

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