- 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 to Print Prime Numbers

In this article, you will learn and get code to print prime numbers using a C++ program in the following ways:

- Print prime numbers between 1 and 100
- At program runtime, print prime numbers between a given range specified by the user

Before creating these programs for the printing of prime numbers, let's first understand them.

### What is a prime number?

If a number can't be divisible by any number except 1 and the number itself, then that number is called a prime number. For example, 2, 3, 5, 7, 13, 17, 19, etc.

## Print prime numbers between 1 and 100

This program prints all prime numbers between 1 and 100 using the **for** loop. The question is, "Write a
program in C++ to print prime numbers from 1 to 100." Here is its answer:

#include<iostream> using namespace std; int main() { int i, chk=0, j; cout<<"Prime Numbers Between 1 to 100 are:\n"; for(i=1; i<=100; i++) { for(j=2; j<i; j++) { if(i%j==0) { chk++; break; } } if(chk==0 && i!=1) cout<<i<<endl; chk = 0; } cout<<endl; return 0; }

This program was built and runs under the Code::BlocksĀ IDE. Here is its sample output:

The dry run of the above program goes like this:

- Initial value,
**chk=0** - Now
**1**gets initialized to**i**, and the condition**i<=100**or**1<=100**evaluates to be true. Therefore, program flow goes inside the loop. - Inside the loop, there is another
*for*loop, so**2**gets initialized to**j**, and the condition**j<i**or**2<1**evaluates to be false, therefore program flow does not go inside this loop's body. - Now the condition of the
**if**gets evaluated. There are two conditions, and between these two conditions, we've used the**&&**operator. As a result, program flow only execute the**if**'s body statement until both conditions are true. - But this time, its first condition, which is
**chk==0**or**0==0**, evaluates to be true, but its second condition, which is**i!=1**or**1!=1**, evaluates to be false, therefore program flow does not go inside its body. - Now
**0**gets initialized to**chk**, and the program flow goes to the update part of the outer*for*loop, which increments the value of**i**. So**i=2** - The condition
**i<=100**or**2<=100**again evaluates to be true, therefore program flow again goes inside the loop. **2**gets initialized to**j**, and the condition**j<i**or**2<2**evaluates to be false.- Now the condition of
**if**, that is,**chk==0**or**0==0**, evaluates to be true, and its second condition,**i!=1**or**2!=1**also evaluates to be true. Since both conditions evaluates to be true, program flow goes inside its body, and the value of**i**gets printed as a prime number, which is**2**. - Now
**0**gets initialized to**ch**, and program flow goes to the update part of the*for*loop and increments the value of**i**. So**i=3** - The condition
**i<=100**or**3<=100**again evaluates to be true, therefore program flow again goes inside the loop. - This process continues until the condition is evaluated as false.
- In this way, prime number gets printed one by one.

## C++ Print Prime Numbers in a Given Range

To print all prime numbers between a particular range (entered by the user) in C++ programming, do a divisibility test (as done in the previous program) using a for loop, from 2 to one less than that number (i.e., n-1). If the number is divided by any number from 2 to one less than that, then the number will not be prime. Otherwise, print it as a prime number, as shown here in the following program.

#include<iostream> using namespace std; int main() { int st, en, i, j, chk=0; cout<<"Enter the Range\n"; cout<<"Enter the Starting Number: "; cin>>st; cout<<"Enter the Ending Number: "; cin>>en; cout<<"\nPrime Numbers between "<<st<<" and "<<en<<" are:\n"; for(i=st; i<=en; i++) { for(j=2; j<i; j++) { if(i%j==0) { chk++; break; } } if(chk==0 && i!=1) cout<<i<<endl; chk = 0; } cout<<endl; return 0; }

Here is the initial output of this program's sample run:

Now enter the two numbers, say 10 and 50, as the starting and ending numbers to print all prime numbers between 10 and 50, as shown in the screenshot below:

#### The same program in different languages

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