Change negative numbers to null

Hello there,

I'm newb in C. My problem is I've to make a function with one array which contains 20 positive and negative numbers. Function in this array will replace all negative values ​​with zeros, nonnegative numbers remain unchanged.

I just tried do something myself, but I think I'm going wrong way. Also can somebody explain me why I cannot put in array something like this?

int numbers[]={'1','-20'};

It gave me error "warning: multi-character character constant [-Wmultichar]"

#include <stdio.h>
#define KZ 1,2,3,4,3,4,5,6,7,8,9,-10,-11,-12,-13,-14,-15,-16,-17,-18,-19,-20

int main(){

  int numbers[]={KZ};
  int i,n;

  for(n=0;n>20;n++){
    printf("Numbers are: %d\n",numbers[n]);
  }

  for(i=0;i>20;i++){
    if(numbers[i]>0)
      printf("0");
    else
      printf("%i",numbers[i]);
  }

  getch();
}