2-5

2-5.c

#include <stdio.h>

int any(char s1[], char s2[]);

int main(){
  //"abcdefg"
  //"cde" -> 2
  //"cdf" -> -1
  printf("1:%d\n", any("abcdef", "cde"));
  printf("2:%d\n", any("abcdef", "cdf"));
}

int any(char s1[], char s2[]){
  int s2size;
  for(s2size = 0; s2[s2size] != '\0' ; s2size++){
  }
  int i, j;
  int matchedsize = 0;
  for(i = 0, j = 0 ; s1[i] != '\0'; i++){
    if(s1[i] == s2[j]){
//      printf("a:%c%c:%d\n", s1[i], s2[j],i);
      matchedsize++;
      j++;
      if(matchedsize == s2size){
        return i - (s2size - 1);
      }
    }else{
      matchedsize = 0;
      j = 0;
    }
  }
  return -1;
}