Counting number of lines in the file in C

Question

I'm writing a function that reads the number of lines in the given line. Some text files may not end with a newline character.

int line_count(const char *filename)
{
   int ch = 0;
   int count = 0;    
   FILE *fileHandle;

   if ((fileHandle = fopen(filename, "r")) == NULL) {
      return -1;
   }

   do {
      ch = fgetc(fileHandle);
      if ( ch == '\n')
         count++;
   } while (ch != EOF);

   fclose(fileHandle);

   return count;
}

Now the function doesn't count the number of lines correctly, but I can't figure out where the problem is. I would be really grateful for your help.

" doesn't count the number of lines correctly" - elaborate.... — Karoly Horvath, Apr 20 '15 at 15:19
when there is a file with 1 line it, the function returns 0. — caddy-caddy, Apr 20 '15 at 15:24
If it's simply that you are off by 1 when there is no trailing newline, you will need to keep track of what the previous character is (e.g. the character before the EOF) and add 1 if it is not a newline. — pens-fan-69, Apr 20 '15 at 15:34

score 4 · Answer 1 · answered Apr 20 '15 at 15:43

Here is another option (other than keeping track of last character before EOF).

int ch;
int charsOnCurrentLine = 0;

while ((ch = fgetc(fileHandle)) != EOF) {
    if (ch == '\n') {
        count++;
        charsOnCurrentLine = 0;
    } else {
        charsOnCurrentLine++;
    }
}
if (charsOnCurrentLine > 0) {
    count++;
}

score 1 · Accepted Answer · edited Jan 26 '21 at 18:26

1

fgets() reads till newline character or till the buffer is full

char buf[200];
while(fgets(buf,sizeof(buf),fileHandle) != NULL)
{
  count++;
}

fgetc() is an issue here because you encounter EOF first and exit your do while loop and never encounter a \n character so count remains untouched for the last line in your file.If it happens to be there is a single line in your file that the count will be 0

edited Jan 26 '21 at 18:26

MattSt

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answered Apr 20 '15 at 15:26

Gopi

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what if there are two lines, not one? – Karoly Horvath Apr 20 '15 at 15:37
@KarolyHorvath Again we see the same issue !! That's the reason I suggested fgets() – Gopi Apr 20 '15 at 15:39

Counting number of lines in the file in C

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