- C++ Programming Examples
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- 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
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- 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
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- C++ Sum of Squares of Digits
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- C++ if else Programs
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- C++ Check Prime or Not
- C++ Check Alphabet or Not
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- C++ Check Leap Year or Not
- Check Reverse equal Original
- C++ Check Perfect Number
- C++ Check Palindrome or Not
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- 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
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- C++ Octal to Binary
- C++ Octal to Hexadecimal
- C++ Hexadecimal to Decimal
- C++ Hexadecimal to Binary
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- C++ Pattern Programs
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- C++ Print Diamond Pattern
- C++ Print Floyd's Triangle
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- C++ Array Programs
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- Find Largest Element in Array
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- 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
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- C++ Merge two Arrays
- C++ Bubble Sort
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- C++ Common Elements
- C++ 2D Array Programs
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- C++ Transpose Matrix
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- C++ Find Length of String
- C++ Compare Two Strings
- C++ Copy String
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- 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
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- C++ Read & Display File
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# C++ Program to Print Prime Numbers

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

- Print Prime Numbers between 1 to 100
- Print Prime Numbers in a Given Range by user at run-time

Before creating these programs on printing of prime numbers, let's first understand about it.

### 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 as prime number. For example, 2, 3, 5, 7, 13, 17 19 etc.

## Print Prime Numbers between 1 to 100

This program prints all prime numbers between 1 to 100 using *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 build and run under *Code::Blocks* IDE. Here is its sample output:

The dry run of above program goes like:

- 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 goes inside this loop's body - Now the condition of
**if**gets evaluated. There are two conditions, and between these two conditions, we've used**&&**operator. So that, program flow only execute the statement of**if**'s body until its both conditions evaluates to be true - But this time, its first condition that is
**chk==0**or**0==0**evaluates to be true, but its second condition, that is**i!=1**or**1!=1**evaluates to be false, therefore program flow does not goes inside its body - Now
**0**gets again initialized to**chk**and program flow goes to the update part of outer*for loop*and 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 its both condition evaluates to be true, therefore program flow goes inside its body and the value of**i**gets printed as prime number, that is**2** - Now
**0**gets initialized to**ch**and program flow goes to update part of*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 evaluates to be false
- In this way, prime number gets printed one by one

## Print Prime Numbers in a Given Range

To print all prime numbers between a particular range (entered by user) in C++
programming, do divisibility test (as done in previous program) using *for loop*, from 2 to one less than that
number (i.e., n-1). If the number is divided to any number from 2 to one less than that number, 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 supply the two numbers as starting number and ending number say **10** and **50** to print all prime
numbers between 10 and 50 as shown in the snapshot given below:

#### Same Program in Other Languages

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