C program to find diameter, circumference and area of circle

Basic C Exercises

C Basics C Programming Tutorial Basic C Exercises Bitwise Operator Exercises Conditional Operator Exercises If else Exercises Switch case Exercises Loop Exercises Star Patterns Number Patterns Functions Exercises Array Exercises String Exercises Pointer Exercises File handling Exercises Data Structures

• C Programming Exercises
• Basic C programming exercises
• Bitwise operator exercises
• Conditional operator exercises
• If else exercises
• Switch case exercises
• Loop and iteration exercises
• Star patterns exercises
• Number pattern exercises
• Functions and recursion exercises
• Array and Matrix exercises
• String exercises
• Pointer exercises
• Files handling exercises

C program to find diameter, circumference and area of circle

Write a C program to input radius of a circle from user and find diameter, circumference and area of the circle. How to calculate diameter, circumference and area of a circle whose radius is given by user in C programming. Logic to find diameter, circumference and area of a circle in C.

Required knowledge

Data Types in c, Input/Output in C, C Operators, Constants in C

Properties of circle

Diameter, circumference and area of a circle formula is given by -

D=2r

C=2πr

A= πr²

Where 'r' is radius of the circle.

Logic to find diameter, circumference and area of circle

Below is the step by step descriptive logic to find diameter, circumference and area of a circle -

1. Input radius of circle from user. Store it in a variable say radius.
2. Apply the formulas to calculate diameter, circumference and area. Use diameter = 2 * radius, circumference = 2 * 3.14 * radius and area = 3.14 * radius * radius.
3. 3.Print all resultant value diameter, circumference and area.

Program to find diameter, circumference and area of circle

/**
 * C program to calculate diameter, circumference and area of circle
 */

#include <stdio.h>

int main()
{
    float radius, diameter, circumference, area;
    
    /*
     * Input radius of circle from user
     */
    printf("Enter radius of circle: ");
    scanf("%f", &radius);

    /*
     * Calculate diameter, circumference and area
     */
    diameter = 2 * radius;
    circumference = 2 * 3.14 * radius;
    area = 3.14 * (radius * radius);

    /*
     * Print all results
     */
    printf("Diameter of circle = %.2f units \n", diameter);
    printf("Circumference of circle = %.2f units \n", circumference);
    printf("Area of circle = %.2f sq. units ", area);

    return 0;
}

\n is an escape sequence character used to add new line (move to next line).

Important note: The above program contains a constant value 3.14. It is always recommended to use constant variable to represent such constants. The constant PI is already defined in math.h header file with name M_PI.

Let us rewrite the above program using constant value.

Program to find diameter, circumference and area of circle using PI constant

/**
 * C program to calculate diameter, circumference and area of circle
 */

#include 
#include  // Used for M_PI

int main()
{
    float radius, diameter, circumference, area;
    
    /*
     * Input radius of circle from user
     */
    printf("Enter radius of circle: ");
    scanf("%f", &radius);

    /*
     * Calculate diameter, circumference and area of circle
     */
    diameter = 2 * radius;
    circumference = 2 * M_PI * radius;
    area = M_PI * (radius * radius);

    /*
     * Print all results
     */
    printf("Diameter of circle = %.2f units \n", diameter);
    printf("Circumference of circle = %.2f units \n", circumference);
    printf("Area of circle = %.2f sq. units ", area);

    return 0;
}

%.2f is used to print the fractional value up to two decimal places. You can also use %f to print up to default 6 decimal places.

Important note: C doesn't provides any exponential operator. Hence never play with operations like radius ^ 2 to find power or to evaluate exponents.

Output:

 Enter radius of circle: 10
 Diameter of circle = 20.00 units
 Circumference of circle = 62.79 units
 Area of circle = 314.00 sq. units

Recommended posts

Loop programming exercises index.
Basic programming exercises index.
If else programming exercises index.
Array programming exercises index.
String programming exercises index.
Pointer programming exercises index.
Star Patterns exercises index.
Number Patterns exercises index.
alphabet Patterns exercises index.
series program exercises index.

Follow @NEWSPAPERS_NEW

C Programming