Print prime numbers from 1 to N in reverse order

Input number n till which prime numbers are calculated and displayed in reverse order

Input : number 30
Output : 29 23 19 17 13 11 7 5 3 2

Algorithm

START
Step 1 -> declare variables as n, I, j, flag to 0 as int
Step 2 -> input number in n
Step 3 -> Loop For from i to n and i>1 and i—
   Step 3.1 ->. Inner loop for from j to i/2 and j>=1 and j—
      Statement If %j==0 && j!=1
         Set flag=0
         Break
      End IF
      Else
         Flag=1
      End Else
   Step 3.2 -> end inner Loop For
Step 4 -> statement IF to check flag=1
   Print i
   End IF
Step 5 -> End outer For
STOP

Example

#include <stdio.h>
int main(int argc, char const *argv[]) {
   int n, i, j, flag=0;
   printf("Enter a number\n");
   scanf("%d", &n);
   for(i=n; i>1; i--) {
      for (j = i/2; j >= 1; j--) {
         if(i%j==0 && j!=1) {
            flag = 0;
            break;
         }
         else
         flag = 1;
      }
      if(flag == 1) {
         printf("%d ", i);
      }
   }
   return 0;
}

Output

If we run the above program then it will generate the following output

Enter a number
30
29 23 19 17 13 11 7 5 3 2

Sunidhi Bansal

Updated on 30-Jul-2019 22:30:26

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