Variables, Data Types, Constants and Operators

Source Code from Notes

Example 1


/* program to add two integer values 
   and display result                 */

#include <stdio.h>

main()
{
        /* declare variables */
        int     value1, value2, sum;

        /* assign values and compute the result */
        value1 = 32;
        value2 = 27;
        sum = value1 + value2;

        /* display the result */
        printf("The sum of %d and %d is %d\n",
                               value1,value2,sum);
}

Example 2

Examples of using these format controls


#include <stdio.h>
/* format controls */
main()
{
        printf("single specified character: %c\n",'a');
        printf("ASCII character of decimal 65: %c\n", 65);
        printf("Integer 65 in decimal: %d\n", 65);
        printf("Integer with leading zeros: %04d\n", 65);
        printf("Scientific notation: %e\n",31415.9);
        printf("Floating point: %f\n",314.159);
        printf("Floating point: %0.2f\n",314.159);
        printf("General format: %g\n",3.14);
        printf("General format: %g\n",0.000314);
        printf("String value: %s\n", "Hello");
}

Example 3

This is the example program to calculate the area of a rectangle


#include <stdio.h>

main()
{
        /* type definitions */
        /* 3 variables - length, breadth and area */

        float   length, breadth, area;

        /* input phase - read length and breadth from user */

        printf("Enter the length and breadth\n");
        scanf("%f %f", &length, &breadth);

        /* computation - calculate area */

        area = length * breadth;

        /* output phase */

        printf("The area of the rectangle with length %f and breadth %f is %f
\n", length, breadth, area);

}

Example 4

This example calculates the average value of three numbers entered by the user.



/*Program to calculate the average of three numbers*/
#include <stdio.h>

main()
{
        float   number1,number2,number3;
        float   average;

        /*Enter values*/
        printf("Enter three numbers: ");
        scanf("%f %f %f",&number1,&number2,&number3);

        /*calculate average*/
        average = (number1 + number2 + number3)/3.0;

        /*Output result*/
        printf("The average value of %f %f and %f is %f\n",
                        number1, number2, number3,average);
}

Example 5

This example prompts the user to input a number and then calculates the reciprocal of this number.



/*Program to calculate the reciprocal of a number*/
#include <stdio.h>

main()
{
        float   number;
        float   reciprocal;

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

        /*Calculate reciprocal*/
        reciprocal = 1.0 / number;

        /*output result*/
        printf("The reciprocal of %f is %f\n",
                                 number, reciprocal);
}

Example 6

This example illustrates the use of constants. It calculates the area and circumference of a circle, when given the radius.



/* program to calculate circumference and area of circle */

#include <stdio.h>
#define PI 3.14159

main()
{
        /*define variables*/
        float   radius,circumference,area;

        /*Input radius*/
	printf("Enter the radius: ");
        scanf("%f",&radius);

        /*calculate radius and circumference*/
        circumference = PI * 2 * radius;
        area = PI * radius * radius;

        /*display results*/
        printf("The circumference is %f and the area is %f\n",
                                           circumference,area);
}

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