C program to print area of triangle, square, circle, rectangle and polygon using switch case.

This C program calculates the area of different geometric shapes using a switch case statement. The program provides a menu−driven interface where users can select from triangle, square, circle, rectangle, and parallelogram area calculations.

Syntax

switch (expression) {
    case constant1:
        // statements
        break;
    case constant2:
        // statements
        break;
    default:
        // default statements
        break;
}

Area Formulas

The program uses the following formulas for area calculations −

• Triangle: Using Heron's formula − area = sqrt(s*(s-a)*(s-b)*(s-c)) where s = (a+b+c)/2
• Square: area = side * side
• Circle: area = ? * radius * radius
• Rectangle: area = length * breadth
• Parallelogram: area = base * height

Example

Following is the C program to calculate areas using switch case −

#include <stdio.h>
#include <math.h>

int main() {
    int choice;
    printf("Enter<br>1 to find area of Triangle<br>2 for finding area of Square<br>3 for finding area of Circle<br>4 for finding area of Rectangle<br>5 for Parallelogram<br>");
    scanf("%d", &choice);

    switch (choice) {
    case 1: {
        int a, b, c;
        float s, area;
        printf("Enter sides of triangle<br>");
        scanf("%d%d%d", &a, &b, &c);
        s = (float)(a + b + c) / 2;
        area = (float)(sqrt(s * (s - a) * (s - b) * (s - c)));
        printf("Area of Triangle is %.2f<br>", area);
        break;
    }
    case 2: {
        float side, area;
        printf("Enter Sides of Square<br>");
        scanf("%f", &side);
        area = side * side;
        printf("Area of Square is %.2f<br>", area);
        break;
    }
    case 3: {
        float radius, area;
        printf("Enter Radius of Circle<br>");
        scanf("%f", &radius);
        area = 3.14159 * radius * radius;
        printf("Area of Circle is %.2f<br>", area);
        break;
    }
    case 4: {
        float len, breadth, area;
        printf("Enter Length and Breadth of Rectangle<br>");
        scanf("%f %f", &len, &breadth);
        area = len * breadth;
        printf("Area of Rectangle is %.2f<br>", area);
        break;
    }
    case 5: {
        float base, height, area;
        printf("Enter base and height of Parallelogram<br>");
        scanf("%f %f", &base, &height);
        area = base * height;
        printf("Area of Parallelogram is %.2f<br>", area);
        break;
    }
    default: {
        printf("Invalid Choice<br>");
        break;
    }
    }
    return 0;
}

Output

When the above program is executed, it produces the following output −

Run 1:
Enter
1 to find area of Triangle
2 for finding area of Square
3 for finding area of Circle
4 for finding area of Rectangle
5 for Parallelogram
5
Enter base and height of Parallelogram
2 4
Area of Parallelogram is 8.00

Run 2:
Enter
1 to find area of Triangle
2 for finding area of Square
3 for finding area of Circle
4 for finding area of Rectangle
5 for Parallelogram
3
Enter Radius of Circle
4.5
Area of Circle is 63.62

Key Points

• Each case handles a specific geometric shape with its corresponding formula.
• The break statement prevents fall−through to subsequent cases.
• The default case handles invalid user input.
• Heron's formula is used for triangle area calculation when three sides are given.

Conclusion

This program demonstrates the effective use of switch case statements for menu−driven programs. It provides a clean way to handle multiple area calculations based on user choice while maintaining code readability.