Area and Perimeter Calculator – C Program

Problem Question

The length & breadth of a rectangle and radius of a circle are input through the keyboard. Write a program to calculate the area & perimeter of the rectangle, and the area & circumference of the circle.

Explanation of Problem

We wish to write a program in which the user will enter 3 numerical values which will denote the length & breadth of a rectangle and radius of a circle. Our program shall compute the rectangle’s perimeter, circle’s circumference, and area for both the geometrical figures. The program is a simple input output program.

Code

#include <stdio.h>
/*Area Perimeter Circumference Calculator*
*@Language: ANSI C*
*@Compiler: GNU GCC*
*@IDE: CodeBlocks 12.11*
*@Author: Toxifier*
*@URL: http://letsplaycoding.blogspot.com/*
*@Date: 29-03-2014**/
int main()
{
    float lengthRectangle, breadthRectangle, radiusCircle, perimeterRectangle, circumference, areaRectangle, areaCircle;
    printf("\n\nEnter lenght of the Rectangle: ");
    scanf("%f", &lengthRectangle);
    printf("Enter breadth of the Rectangle: ");
    scanf("%f", &breadthRectangle);
    printf("Enter radius of the Circle: ");
    scanf("%f", &radiusCircle);
    printf("\nCalculating......\n");
    perimeterRectangle = ( lengthRectangle + breadthRectangle ) * 2;
    areaRectangle = lengthRectangle * breadthRectangle;
    circumference = radiusCircle * 2 * 3.14;
    areaCircle = radiusCircle * radiusCircle * 3.14;
    printf("\nArea:\n\tRectangle: %f\n\tCircle: %f\nPerimter:\n\tRectangle: %f\n\tCircle: %f\n", areaRectangle, areaCircle, perimeterRectangle, circumference);
    system("pause");
    return 0;
}

Explanation of Code

#include <stdio.h> -> This is the step which occurs before compilation starts. The compiler calls the C Preprocessor to include the STDIO(Standard Input Output) header file into the program, thus letting the use of the standard input/output functions like printf() and scanf() which come from STDIO.H

int main() -> The entry point of the program where the execution starts. This functions has to named main. As per the ANSI specification, the return type has to be int. If you use the traditional C, you may use void as the return type. Since the return type is specified as int in my program, I have to use a return statement at the end of my code. So I use return 0 since zero returned from a function, by convention, implies a correct execution of the program. The return values are used to debug the program.

printf() -> This is a standard output function used to print something on the screen. We have to pass a string to this function which will be displayed on user's terminal.

scanf() -> This is the scanf() function which waits for the user to enter certain value using his/her keyboard. We store the user input at the location in memory which is pointed to by the variable whose address is passed to this function.

perimeterRectangle = ( lengthRectangle + breadthRectangle ) * 2;
areaRectangle = lengthRectangle * breadthRectangle;
circumference = radiusCircle * 2 * 3.14;
areaCircle = radiusCircle * radiusCircle * 3.14;
These lines of code are the real processing of the program where the calculation of the perimeter, circumference, and area are calculated.

system("pause") -> This statement is used to pause the program, until user presses a key. This function is not necessary in your program, I use it to see my outputs paused. If you use cmd to run your programs, you might not need this. If you use linux/unix you might not need this. Depending on your compiler, this function may or may not work. Moreover, removing this line of code from this program, doesn't affect the functionality of the program.

Output(s)