# Prime Number between Intervals

## Prime numbers

The numbers which are divisible only by 1 and by the number itself are known to be prime numbers. Prime numbers are always greater than 1. The only even prime number is 2 while the rest of the prime numbers are odd.We will learn how to find prime number between intervals.

## Print prime number between intervals:

Step 1 : Take the values of lower limit and upper limit of the interval as input.
Step 2 : Initialize a variable flag with value 0.
Step 3 : Iterate a for loop from lower limit to the upper limit.
Step 4 : Take the value as num.
Step 5 : Now iterate a for loop from 0 to num/2.
Step 6 : If the num is divisible by loop iterator,then increment flag.
Step 7 : If flag = 0 , then prime
else , not prime
Step 8 : Back to Step 4.
Step 9 : End

## Example 1:

Run

```#include<stdio.h>

int main()
{
int a, b, i, j, flag;
printf("Enter lower bound of the interval: ");
scanf("%d", &a);
printf("\nEnter upper bound of the interval: ");
scanf("%d", &b);
printf("\nPrime numbers between %d and %d are: ", a, b);
for (i = a; i <= b; i++) {
if (i == 1 || i == 0)
continue;
flag = 1;
for (j = 2; j <= i / 2; ++j) {
if (i % j == 0) {
flag = 0;
break;
}
}
if (flag == 1)
printf("%d ", i);
}
return 0;
}
```

## Output:

```Enter lower bound of the interval: 1
Enter upper bound of the interval: 15
Prime numbers between 1 and 10 are: 2 3 5 7 11 13
```

## Example 2:

Run
```#include<stdio.h>

int main() {
int low, high, i, flag;
printf("Enter two numbers(intervals): ");
scanf("%d %d", &low, &high);
printf("Prime numbers between %d and %d are: ", low, high);
while (low < high) {
flag = 0;
if (low <= 1) {
++low;
continue;
}
for (i = 2; i <= low / 2; ++i) {

if (low % i == 0) {
flag = 1;
break;
}
}
if (flag == 0)
printf("%d ", 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
```

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