Thread: find a string

Hi!I'm new to C programming and I wanted to ask where is the error in this code:
I have a file text ( frase.txt),placed in the same folder and I have to search for a string in this text and if I find that string I have to print it.

Code:

#include <stdlib.h>
#include <stdio.h>
#include <string.h>


int main(){
const char searchingString[20];
FILE *fillle= fopen("frase","r");

char *s;
char *token;
printf("Introduce the string:");
scanf("%s",searchingString);

while(fgets(s,128,fillle)!=NULL){

token = strtok(s ," ");

if(strcmp(token,searchingString) == 0)
printf("%s\n",searchingString);
else printf("0\n");
while (strtok!=NULL) {
token= strtok(NULL," ");
if(strcmp(token,searchingString) == 0)
printf("%s\n",searchingString);
else printf("0\n");
}
}
}

When I compile the file it doesn't give me any problem and when I try the program it prints on the monitor Introduce the string,but when I give it it says segmentation fault!
What's the problem?thanks!

Sorry for my English!

Code:

char *s;  // This pointer is uninitialized. 
. . .
fgets(s, 128, fillle);  // You're using an uninitialized pointer.

I've changed my code as you've said,but it stills give me the same problem..

Code:

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

int main(){
char searchingString[20]; 
FILE *fillle= fopen("frase","r");
char s[512];
char *token;
printf("Introduce the string:");
scanf("%s",searchingString);
while(fgets(s,512,fillle)!=NULL){
token = strtok(s ," ");
if(strcmp(token,searchingString) == 0)
printf("%s\n",searchingString);
else printf("0\n");
while (strtok!=NULL) {
token= strtok(NULL," ");
if(strcmp(token,searchingString) == 0)
printf("%s\n",searchingString);
else printf("0\n");
}
}
}

strtok != NULL is always true. Perhaps you mean to check while token != NULL -- although, even then, you're one step too late since you use the new value of token before checking it.