└── prime number


/prime number:
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 1 | #include <stdio.h>
 2 | 
 3 | int main() {
 4 | 
 5 |   int n, i, flag = 0;
 6 |   printf("Enter a positive integer: ");
 7 |   scanf("%d", &n);
 8 | 
 9 |   // 0 and 1 are not prime numbers
10 |   // change flag to 1 for non-prime number
11 |   if (n == 0 || n == 1)
12 |     flag = 1;
13 | 
14 |   for (i = 2; i <= n / 2; ++i) {
15 | 
16 |     // if n is divisible by i, then n is not prime
17 |     // change flag to 1 for non-prime number
18 |     if (n % i == 0) {
19 |       flag = 1;
20 |       break;
21 |     }
22 |   }
23 | 
24 |   // flag is 0 for prime numbers
25 |   if (flag == 0)
26 |     printf("%d is a prime number.", n);
27 |   else
28 |     printf("%d is not a prime number.", n);
29 | 
30 |   return 0;
31 | }
32 | 


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