# (C++ programming Example for Beginners)

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

#### Example to print all prime numbers between two numbers (entered by the user) in C++ Programming. This problem is solved using nested for loop and if…else statement.

## 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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