- C++ Programming Examples
- C++ Programming Examples
- C++ Hello World
- C++ Get Input
- C++ Print Integer
- C++ Add Two Numbers
- C++ Add Sub Mul Div
- C++ Add Digits
- C++ Find Average Perc
- C++ Find Arithmetic Mean
- C++ Sum of n Natural Numbers
- C++ Sum of n Numbers
- C++ Area Perimeter of Square
- C++ Area Perimeter of Rectangle
- C++ Area Perimeter of Triangle
- C++ Area Circum of Circle
- C++ Find Simple Interest
- C++ Fahrenheit to Celsius
- C++ Celsius to Fahrenheit
- C++ Print Prime Numbers
- C++ Reverse a Number
- C++ Swap Two Numbers
- C++ Print Multiplication Table
- C++ Find Factorial of Number
- C++ Find Factors of Number
- C++ Find HCF & LCM
- C++ Make Calculator
- C++ Count Digits in Number
- C++ Sum of First & Last Digit
- C++ Product of Digits of Number
- C++ Sum of Squares of Digits
- C++ Interchange Digits of Number
- C++ if else Programs
- C++ Check Even or Odd
- C++ Check Prime or Not
- C++ Check Alphabet or Not
- C++ Check Vowel or Not
- C++ Check Leap Year or Not
- Check Reverse equal Original
- C++ Check Perfect Number
- C++ Check Palindrome or Not
- C++ Check Armstrong or Not
- C++ Divisibility Test
- C++ Find Wage of Labor
- C++ Find Discounted Price
- C++ Find Shipping Charge
- C++ Find Telephone Bills
- C++ Calculate Student Grade
- C++ Largest of Two Numbers
- C++ Largest of Three Numbers
- C++ Number Conversion
- C++ Decimal to Binary
- C++ Decimal to Octal
- C++ Decimal to Hexadecimal
- C++ Binary to Decimal
- C++ Binary to Octal
- C++ Binary to Hexadecimal
- C++ Octal to Decimal
- C++ Octal to Binary
- C++ Octal to Hexadecimal
- C++ Hexadecimal to Decimal
- C++ Hexadecimal to Binary
- C++ Hexadecimal to Octal
- C++ Pattern Programs
- C++ Pattern Programs
- C++ Print Diamond Pattern
- C++ Print Floyd's Triangle
- C++ Print Pascal's Triangle
- C++ Array Programs
- C++ 1D Array Program
- C++ Linear Search
- C++ Binary Search
- Find Largest Element in Array
- Find Smallest Element in Array
- Find Second Largest Element
- Find Second Smallest Element
- C++ Sum of All Elements
- C++ Multiply All Elements
- C++ Element on Even Position
- C++ Element on Odd Position
- C++ Print Even Numbers in Array
- C++ Print Odd Numbers in Array
- C++ Count Even/Odd Numbers
- C++ Sum of Even/Odd Numbers
- C++ Count Positive Negative Zero
- C++ Reverse an Array
- C++ Insert Element in Array
- C++ Delete Element from Array
- C++ Merge two Arrays
- C++ Bubble Sort
- C++ Selection Sort
- C++ Insertion Sort
- C++ Common Elements
- C++ 2D Array Programs
- C++ Add Two Matrices
- C++ Subtract Two Matrices
- C++ Transpose Matrix
- C++ Multiply Two Matrices
- C++ 3D Array Programs
- C++ String Programs
- C++ Print String
- C++ Find Length of String
- C++ Compare Two Strings
- C++ Copy String
- C++ Concatenate String
- C++ Reverse a String
- C++ Delete Vowels from String
- C++ Delete Word from String
- C++ Count Character in String
- C++ Count Word in String
- C++ Frequency of Word
- C++ Remove Spaces from String
- C++ Sort a String
- C++ Uppercase to Lowercase
- C++ Lowercase to Uppercase
- C++ Swap Two Strings
- C++ Check Anagram or Not
- C++ Capitalize All Words in String
- C++ Capitalize Specific Character
- C++ Get Numbers from String
- C++ File Programs
- C++ Read a File
- C++ Write Content to File
- C++ Append Data in File
- C++ Read & Display File
- C++ Copy a File
- C++ Merge Two Files
- Count Characters, Words in File
- C++ Capitalize All Words in File
- C++ List Files in Directory
- C++ Delete a File
- C++ Encrypt & Decrypt a File
- C++ Misc Programs
- C++ Print ASCII Value
- C++ Add Binary Numbers
- C++ Generate Random Numbers
- C++ Print Smiling Face
- C++ Days into Years, Months
- Add Two Numbers using Pointer
- C++ Print Fibonacci Series
- Generate Armstrong Numbers
- C++ Find nCr and nPr
- C++ Get IP Address
- C++ Print Date/Time
- C++ Shutdown, Restart Computer
- C++ Programming Tutorial
- C++ Tutorial
- C++ Programming Test
- C++ Programming Test
- Give Online Test
- All Test List
C++ Program to Find Area, Circumference of Circle
In this article, you will learn and get code on finding the area and circumference of a circle based on its radius entered by user at run-time in C++ programming. Here are the list of approaches used:
- Area of Circle without using Function
- Area of Circle using Function
- Circumference of Circle without using Function
- Circumference of Circle using Function
- Area and Circumference of Circle using Class
Before starting the program, let's first get the formula used to find area and circumference of a circle.
Area of Circle Formula
To find area of a circle, use this formula:
area = 3πr2
The value of π is 3.14. And r indicates radius of circle. This formula can also be written as:
area = 3*3.14*r*r
Circumference of Circle Formula
To find circumference of a circle, use this formula:
circumference = 2πr
Now let's move on to the program.
Find Area of Circle
To calculate area of any circle in C++ programming, you have to ask from user to enter the radius of circle, place the radius in a variable say rad and then initialize 3.14*rad*rad in a variable that holds the value of area of circle, as shown here in the following program.
#include<iostream> using namespace std; int main() { float rad, area; cout<<"Enter the Radius of Circle: "; cin>>rad; area = 3.14*rad*rad; cout<<"\nArea of Circle = "<<area; cout<<endl; return 0; }
This program was build and run under Code::Blocks IDE. Here is its sample run:
Now enter the radius of circle say 5 and press ENTER
key to see the following output:
You can also replace the variable rad with r to make above program more meaningful.
Using Function
Let's create the same purpose program using a user-defined function findArea(). This function takes radius as its argument and returns the area of circle. The question is, write a program in C++ to find the area of a circle using user-defined function. Answer to this question is given below:
#include<iostream> using namespace std; float findArea(float); int main() { float rad, area; cout<<"Enter the Radius of Circle: "; cin>>rad; area = findArea(rad); cout<<"\nArea of Circle = "<<area; cout<<endl; return 0; } float findArea(float r) { return (3.14*r*r); }
It will produce the same output as of previous one.
Find Circumference of Circle
The question is, write a program in C++ to find circumference of a circle. The answer to this question is:
#include<iostream> using namespace std; int main() { float rad, circum; cout<<"Enter the Radius of Circle: "; cin>>rad; circum = 2*3.14*rad; cout<<"\nCircumference of Circle = "<<circum; cout<<endl; return 0; }
Here is the initial snapshot of the sample run:
Now enter the radius of circle to see its circumference. Here is the final snapshot of sample run, supposing that user enters 5 as radius of circle:
Using Function
This program does the same job as of previous program, but using a function named findCircum()
#include<iostream> using namespace std; float findCircum(float); int main() { float rad; cout<<"Enter the Radius of Circle: "; cin>>rad; cout<<"\nCircumference of Circle = "<<findCircum(rad); cout<<endl; return 0; } float findCircum(float r) { return (2*3.14*r); }
This program produces the same output as of previous one.
Find Area and Circumference using Class
This is the last program of this article. This program finds both area and circumference of a circle using an object oriented feature of C++, that is class.
#include<iostream> using namespace std; class CodesCracker { public: float findArea(float r) { return (3.14*r*r); } float findCircum(float r) { return (2*3.14*r); } }; int main() { CodesCracker c; float rad, area, circum; cout<<"Enter the Radius of Circle: "; cin>>rad; area = c.findArea(rad); circum = c.findCircum(rad); cout<<"\nArea of Circle = "<<area; cout<<"\nCircumference of Circle = "<<circum; cout<<endl; return 0; }
Here is the sample run of above program with user input as 5 (radius of circle):
To learn more about class, you can follow the separate tutorial on it. Above program can also be written as:
#include<iostream> using namespace std; class CodesCracker { private: float r; public: void getData(); float findArea(); float findCircum(); }; void CodesCracker::getData() { cout<<"Enter the Radius of Circle: "; cin>>r; } float CodesCracker::findArea() { return (3.14*r*r); } float CodesCracker::findCircum() { return (2*3.14*r); } int main() { CodesCracker c; c.getData(); cout<<"\nArea of Circle = "<<c.findArea(); cout<<"\nCircumference of Circle = "<<c.findCircum(); cout<<endl; return 0; }
Same Program in Other Languages
- C Find Area & Circumference
- Java Find Area & Circumference
- Python Find Area & Circumference
- Python Find Circumference
« Previous Program Next Program »