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.

Solution 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

Solution 2

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++;
}

Comments

[Karoly Horvath]

" doesn't count the number of lines correctly" - elaborate....

[caddy-caddy]

when there is a file with 1 line it, the function returns 0.

[pens-fan-69]

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.

[Karoly Horvath]

what if there are two lines, not one?

[Gopi]

@KarolyHorvath Again we see the same issue !! That's the reason I suggested fgets()