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  1. #include <stdio.h>
  2. int main() {
  3.     int n, i, flag = 0;
  4.     printf("Enter a positive integer: ");
  5.     scanf("%d", &n);
  6.  
  7.     for (i = 2; i <= n / 2; ++i) {
  8.  
  9.         // condition for non-prime
  10.         if (n % i == 0) {
  11.             flag = 1;
  12.             break;
  13.         }
  14.     }
  15.  
  16.     if (n == 1) {
  17.         printf("1 is neither prime nor composite.");
  18.     }
  19.     else {
  20.         if (flag == 0)
  21.             printf("%d is a prime number.", n);
  22.         else
  23.             printf("%d is not a prime number.", n);
  24.     }
  25.  
  26.     return 0;
  27. }
Success #stdin #stdout 0s 4376KB
comments (?)
stdin
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7
stdout
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Enter a positive integer: 7 is a prime number.
https://ideone.com/27nptz
language:
C (clang 8.0)
created:
3 years ago
visibility:
public

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