c 筛法列举质数

 

 

#include <stdio.h>

int main() {
    int n = 15;
    int mark[16] = {
        1, 1, 0, 0,
        0, 0, 0, 0,
        0, 0, 0, 0,
        0, 0, 0, 0
    };
    int c;
    int j;

    for (c = 2; c * c <= n; c++) {
       if(mark[c]!=1){
         for(j=2;j<=n/c;j++){
            mark[c*j]=1;
         }
       }
    }

    for(c=2;c<=n;c++){
      if(mark[c]!=1){
         printf("%d\n",c);
      }
    }
    return 0;
}