C程序中的段错误

Question

I had a program over 300 lines that worked 100% except for an fclose that caused a seg fault... Now, I can't even get my program to run at all. gdb gave me this error, which I honestly don't know how to interpret

    ____strtol_l_internal (nptr=0x0, endptr=0x0, base=10,
       group=<value optimized out>, loc=0x349c78d580) at ../stdlib/strtol_l.c:298
       298       while (ISSPACE (*s))

Can anyone tell me what this means?

 readLinesFromFile(FILE* fPtr, int* num1, int* num2, char** strs, int lines)
 {
  int i;

  char data[50];

for (i = 0; i < lines; i++){
    fgets(data, 50, fPtr);
    strcpy (*(strs + i), strtok(data, " "));
    *(num1 + i) = atoi(strtok(NULL, " "));
    *(num2 + i) = atoi(strtok(NULL, " "));
}

Answer 1

Are you sure the SIGSEGV is triggered when you call an fclose ?

It looks like you're simple passing a NULL pointer as first parameted of strtol function (in some other part of the code)

Another option could be a stack totally messed up.

Try to run it with gdb and when it crash use the command where to see the stack