Question

How to find the max prime number in an array with C

Answer 1

#include <stdio.h>
#include <math.h>
 
int isPrime(int n) {
    if (n == 0) return 0;
    if (n == 1) return 0;
    
    for (int i = 2; i <= sqrt(n); i++) {
        if (n % i == 0)
            return 0;
    }
    
    return 1;
} 
 
int main() {
 
    int arr[] = {4, 8, 17, 5, 9, 22, 21, 13, 18, 99};
    int len = sizeof(arr) / sizeof(int), max = arr[0];
 
    for (int i = 0; i < len; i++) {
        if (isPrime(arr[i])) { // 17 5 13
            if (max < arr[i]) { 
                max = arr[i];
            }
        }
    }
     
    printf("%d", max);
 
    return 0;
}

  
  
/*
run:
  
17
 
*/

 

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