Question

I’ve created this function to read a word. I got segmentation fault and I can’t find the problem. Here’s what I’ve done.

void LeeCaracter(FILE * fp, char * s)

{

    char c;
    int i = 0;

    c = fgetc(fp);
    while(c==' ' || c=='\t' || c=='\n')
        c = fgetc(fp);
    while(c!=' ' && c!='\n')
      {
          s[i] = c;
          i++;
          c = fgetc(fp);

      }
    s[i] = '\0'; 
}

s is a pointer parameter, as I have to use it later. Is it correct to write it just with one *? Thanks for your help!

*And what about if I wanted to know the character that follows the word(‘ ‘ or ‘\n’)? I added this after the while loop:
“printf(“%c”,c);”
but it doesn’t print anything. Any ideas?

Answer 1

You have to make sure that the ‘s’ has enough space for containing a word with maximum characters in the input file. Then you need to make sure that you check for ‘End Of File’. Here is a working version. I hope it works for you as well.

#include <stdio.h>

void LeeCaracter(FILE * fp, char * s)
{
  char c;
  int i = 0;

  c = fgetc(fp);
  if (feof(fp)) return;
  while (c == ' ' || c == '\t' || c == '\n')
    c = fgetc(fp);
  while (!feof(fp) && (c != ' ' && c != '\n')) {
    s[i++] = c;
    c = fgetc(fp);
  }
  s[i] = '\0'; 

  printf("%s\n", s);
}

int main(void)
{
  char s[128]; /* assuming no word is larger than this size */
  FILE *fp = fopen("/usr/share/dict/words", "r");

  while (!feof(fp)) {
    LeeCaracter(fp, s);
  }

  return 0;
}