How to implement squeeze functionality of 'cat' command using c?

Question

The following is a part of my program trying to implement 'squeeze' or '-s' of 'cat' command using c. Now the main function uses argv and argc, which are analysed by using getopt function.'squeeze' function is called in main and 'stdin' and 'stdout' are passed as arguments. also the return type of getopt function is passed in writeLineNumbers. I am just wondering if this is the right way to do it?

void squeeze ( FILE *fin, FILE *fout, int writeLineNumbers)
{
    char line[len];
    //int linenumber=1;

    while (fgets(line,len,fin))
    {
        if(line==NULL)
            fin--=fin;
        if (fputs(line, fout)==EOF)
        {
            printf(stderr,"Write to stdout failed.");
            return;
        }
       // ++linenumber;
    }

}

Answer 1

Try this :

   void squeeze (FILE *fin, FILE *fout, int writeLineNumbers)
    {
    char line[len] = {0};

    while (fgets(line, len, fin))
    {
        if(strlen(line) != 0)
        {
          if (fputs(line, fout) == EOF)
          {
            printf(stderr,"Write to stdout failed.");
            return;
        }
    }
}