Algorithm

  1. Input lower and upper bounds of the interval.
    2. For each number i in the interval from lower to upper:
       a. Check if i is a prime number.
          i. If i is less than or equal to 1, skip to the next iteration.
          ii. For j from 2 to the square root of i:
              - If i is divisible by j, i is not a prime number. Skip to the next iteration.
          iii. Display i as a prime number.
    3. End.

Code Examples

#1 Code Example-C Programing Display Prime Numbers Between Two Intervals

Code - C Programming

#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);

   // iteration until low is not equal to high
   while (low < high) {
      flag = 0;

      // ignore numbers less than 2
      if (low <= 1) {
         ++low;
         continue;
      }

      // if low is a non-prime number, flag will be 1
      for (i = 2; i <= low / 2; ++i) {

         if (low % i == 0) {
            flag = 1;
            break;
         }
      }

      if (flag == 0)
         printf("%d ", low);

      // to check prime for the next number
      // increase low by 1
      ++low;
   }

   return 0;
}
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Output

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

#2 Example-Display Prime Numbers when Larger Number is Entered first

Code - C Programming

#include <stdio.h>

int main() {
   int low, high, i, flag, temp;
   printf("Enter two numbers(intervals): ");
   scanf("%d %d", &low, &high);

   // swap numbers if low is greather than high
   if (low > high) {
      temp = low;
      low = high;
      high = temp;
   }

   printf("Prime numbers between %d and %d are: ", low, high);
   while (low < high) {
      flag = 0;

      // ignore numbers less than 2
      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;
}
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Demonstration

C Programing Example to Display Prime Numbers Between Two Intervals-DevsEnv

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