Thread: Returning found from main

Good afternoon. what's the meaning of returning non-zero from main?

Code:

 

/* strindex: return index of t in s, -1 if none */ 
 
#include <stdio.h> 

#include "Headers/strings.h"
#include "Strings/strindex.c"
#include "Strings/getline.c"

#ifndef MAXLINE 
  #define MAXLINE 1000
#endif  

static const char pattern[] = "ould";
int found;

int main(void) 
{ 
  char line[MAXLINE];
  
  while(getLine(line,MAXLINE) > 0)
   if(strindex(line, pattern) >= 0)
     printf("%s", line); 
   found++;  
  
  return found;    
}