counting the number of times a character appears in a file in a case insensitive manner using C language -

the problem statement : c program count number of times character appears in file. character considered case insensitive. have converted both input character , character file upper case none of occurrence of character goes uncounted. when executing on online editor getting result "wrong answer" editor isn`t accepting code. mistake in code??

    #include<stdio.h>     #include<ctype.h>     #include<stdlib.h>     int main     {      file *fp;      char filename[20];      char character;      char compare;      int to_upper1;      int to_upper2;      int count=0;      printf("\nenter file name");      scanf("%s", filename);      fp = fopen(filename,"r");      if(fp == null)      {        exit(-1);      }      printf("\nenter character counted");      scanf("%c", &character);      to_upper1 = toupper(character);      while((compare = fgets(fp)) != eof)      {        to_upper2 = toupper(compare);        if(to_upper1 == to_upper2)           count++;      }      printf("\nfile \'%s\' has %d instances of letter \'%c\'", filename, count,      character); return 0; } 

i found few errors in code, , made few small tweaks. errors - not eating "whitespace" before character input, using fgets() instead of fgetc(), using escape characters before ' symbols in output text.

#include <stdio.h> #include <ctype.h> #include <stdlib.h>  int main(void)                                  // added arg compilability {     file *fp;     char filename[20];     char character;     int compare;                                // correct type fgetc , toupper     int to_upper1;     int to_upper2;     int count=0;     printf("enter file name: ");     scanf("%19s", filename);                    // restrict length     fp = fopen(filename,"r");     if(fp == null)     {         printf ("cannot open file '%s'\n", filename);         exit(-1);     }     printf("\nenter character counted: ");     scanf(" %c", &character);                   // filter out whitespace     to_upper1 = toupper((int)character);     while((compare = fgetc(fp)) != eof)         // changed fgets()     {         to_upper2 = toupper(compare);         if(to_upper1 == to_upper2)           count++;     }     fclose(fp);                                 // remember close file!     printf("file '%s' has %d instances of letter '%c'", filename, count, character);     return 0; }