- C++ Programming Examples
- C++ Programming Examples
- C++: Hello World
- C++: Get Input
- C++: Print Integer
- C++: Add two numbers
- C++: Add, Sub, Multiply, Div
- C++: Add Digits
- C++: Find Average and Percentage
- C++: Find Arithmetic Mean
- C++: Sum of n Natural Numbers
- C++: Sum of n Numbers
- C++: Square's Area and Perimeter
- C++: Rectangle's Area and Perimeter
- C++: Triangle's Area and Perimeter
- C++: Area and Circumference
- 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 a Number
- C++: Find Factors of a Number
- C++: Find HCF and LCM
- C++: Create a Calculator
- C++: Count Digits in a Number
- C++: First and Last Digit Sum
- C++: Product of Number Digits
- 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
- C++: Check Reverse equals Original
- C++: Check Perfect Number
- C++: Check Palindrome or Not
- C++: Check Armstrong or Not
- C++: Divisibility Test
- C++: Find Labor Wage
- 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
- C++: Largest Element in an Array
- C++: Smallest Element in an Array
- C++: Find Second Largest Element
- C++: Find Second Smallest Element
- C++: Sum of All Elements
- C++: Multiply All Elements
- C++: Element in Even Position
- C++: Element in Odd Position
- C++: Print Even Numbers in Array
- C++: Print Odd Numbers in Array
- C++: Count Even or Odd Numbers
- C++: Sum of Even or Odd Numbers
- C++: Count Positive, Negative, Zero
- C++: Reverse an Array
- C++: Insert an Element
- C++: Delete an Element
- 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 String Length
- C++: Compare Two Strings
- C++: Copy String
- C++: String Concatenation
- C++: Reverse a String
- C++: Delete Vowels from a String
- C++: Delete a Word from a String
- C++: Count Characters in a String
- C++: Count Words in a String
- C++: Frequency of Words
- C++: Remove Spaces from Strings
- C++: Sort a String
- C++: Uppercase to Lowercase
- C++: Lowercase to Uppercase
- C++: Swap Two Strings
- C++: Check the Anagram or Not
- C++: Capitalize All Words in a String
- C++: Get Numbers from a String
- C++ File Programs
- C++: Read a File
- C++: Write Content to a File
- C++: Append Data to a File
- C++: Read and Display File
- C++: Copy a File
- C++: Merge Two Files
- Count Characters in a File
- C++: Capitalize Every Word
- C++: List Files in Directory
- C++: Delete a File
- C++: Encrypt and Decrypt a File
- C++ Misc Programs
- C++: Print ASCII Value
- C++: Add Binary Numbers
- C++: Generate Random Numbers
- C++: Print a Smiling Face
- C++: Days into Years and Months
- C++: Add Two Numbers using Pointer
- C++: Print Fibonacci Series
- C++: Generate Armstrong Numbers
- C++: Find nCr and nPr
- C++: Get IP Address
- C++: Print Date and Time
- C++: Shutdown and Restart Computer
- C++ Programming Tutorial
- C++ Tutorial
C++ Program for Calculating the Area and Circumference of a 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 the user at run-time in C++ programming. Here is the list of approaches used:
- Without using a function, calculate the area of a circle
- Area of a Circle using Function
- Circumference of a circle without using function
- Circumference of a circle using function
- Circle Area and Circumference Using Class
Before starting the program, let's first review the formula used to find the area and circumference of a circle.
Circle Area Formula
To find the area of a circle, use this formula:
area = 3πr2
3.14 is the value of π. And r denotes the circle's radius. This formula can also be written as:
area = 3*3.14*r*r
Circumference of a Circle Formula
To find the circumference of a circle, use this formula:
circumference = 2πr
Now let's move on to the program.
Calculate the Area of a Circle
To calculate the area of any circle in C++ programming, you have to ask the user to enter the radius of the circle, place the radius in a variable, say rad, and then initialize 3.14*rad*rad in a variable that holds the value of the area of the 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 built and runs under the Code::Blocks IDE. Here is its sample run:
Now enter the radius of the circle, say 5, and press the ENTER key to see the following output:
You can also replace the variable rad with r to make the above program more meaningful.
In C++, find the area of a circle using a function
Let's create the same-purpose program using a user-defined function, findArea(). This function takes the radius as its argument and returns the area of the circle. The question is: write a program in C++ to find the area of a circle using a user-defined function. The 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 the previous one.
Find the Circumference of a Circle in C++
The question is, "Write a program in C++ to find the 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 the circle to see its circumference. Here is the final snapshot of the sample run, supposing that the user enters 5 as the radius of the circle:
Find the circumference of a circle in C++ using Function
This program does the same job as the previous program but uses 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 the previous one.
Using a class, calculate the area and circumference in C++
This is the end of this article. This program finds both the area and circumference of a circle using an object-oriented feature of C++, namely classes.
#include<iostream> using namespace std; class fresherearth { public: float findArea(float r) { return (3.14*r*r); } float findCircum(float r) { return (2*3.14*r); } }; int main() { fresherearth 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 the above program with user input of radius 5:
The above program can also be written as:
#include<iostream> using namespace std; class fresherearth { private: float r; public: void getData(); float findArea(); float findCircum(); }; void fresherearth::getData() { cout<<"Enter the Radius of Circle: "; cin>>r; } float fresherearth::findArea() { return (3.14*r*r); } float fresherearth::findCircum() { return (2*3.14*r); } int main() { fresherearth c; c.getData(); cout<<"\nArea of Circle = "<<c.findArea(); cout<<"\nCircumference of Circle = "<<c.findCircum(); cout<<endl; return 0; }
The same program in different languages
- C Find Area & Circumference
- Java Find Area & Circumference
- Python Find Area & Circumference
- Python Find Circumference
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