关于从C中的文本文件读取char数组的任何建议？

Question

Here's my issue I'm running into.

I'm reading in lines of text from a file, but only trying to read in lines that aren't consecutive repeats.

Here's my regular code for reading in the lines of text.

  while (((ch = getc (fp)) != EOF))
         {
            a[j++] = ch;
         }   
          a[j] = '\0';

which works just fine.

When trying to figure out how to go about the problem, I tried having a char array that would read in a line at a time, and then compare it to the previous line using strcomp. If it was a match, it would not add that line into the final char array. It looks something like this:

  while (((ch = getc (fp)) != EOF))
        {
            if (ch != '\n')
            {
            copynumber++;
            temp[j] = ch;
            }
            else 
            {
            uni = strcmp(identical, final);
                if (uni == 0) {
                    copynumber = 0;
                }
                else 
                {
                    strncpy(identical, temp, copynumber);
                    final[j] = ch;
                }
                j++;
            }

        }
          final[j] = '\0';

but I know this won't work for a few reasons. One, I never add the previous chars into the final array. I'm really just lost. Any help is appreciated. Thank you.

Answer 1

There is a getline() function in stdio.h that you can use to get each line in a file.

To skip duplicates you can store the previous line read and compare at each step.

FILE *fp;
char *line = NULL;
char *prev_line[999];
char final[999];
size_t len = 0;
ssize_t read;

fp = fopen("file", "r");

while ((read = getline(&line, &len, fp)) != -1) { // Read each line
    if (strncmp(line, prev_line, read) != 0) {    // If not equal
        strncat(final, line, read);                // Copy to final
        strncpy(prev_line, line, read);           // Update previous
    }
}

free(line); // Need to free line since it was null when passed to getline()