# C++ Program to Display Prime Numbers Between Two Intervals

## Example #1: Display Prime Numbers Between two Intervals

``````
#include <iostream>
using namespace std;

int main(){
int low, high, i, flag;

cout << "Enter two numbers(intervals): ";
cin >> low >> high;

cout << "Prime numbers between " << low << " and " << high << " are: ";

while (low < high)
{
flag = 0;

for(i = 2; i <= low/2; ++i)
{
if(low % i == 0)
{
flag = 1;
break;
}
}

if (flag == 0)
cout << low << " ";

++low;
}

return 0;
}
``````

Output

`Enter two numbers(intervals): 20 50 Prime numbers between 20 and 50 are: 23 29 31 37 41 43 47`

In this program, the while loop is iterated `(high - low - 1)` times.

In each iteration, whether low is a prime number or not is checked and the value of low is incremented by 1 until low is equal to high.

## Example #2: Display Prime Numbers When Larger Number is Entered first

``````
#include <iostream>
using namespace std;

int main(){
int low, high, flag, temp;

cout << "Enter two numbers(intevals): ";
cin >> low >> high;

//swapping numbers if low is greater than high
if (low > high) {
temp = low;
low = high;
high = temp;
}
cout << "Prime numbers between " << low << " and " << high << " are: ";

while (low < high)
{
flag = 0;

for(int i = 2; i <= low/2; ++i)
{
if(low % i == 0)
{
flag = 1;
break;
}
}
if (flag == 0)
cout << low << " ";

++low;
}
return 0;
}``````

## C++ for Beginners: C++ Program to Display Prime Numbers Between Two Intervals

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