How do I count lines, words and keywords in a text file

my task is to count the number of lines, words and keywords present in a text file. i was able to get the lines and the words counted, but i was unable to count the KEYWORDS present in the text file. there are 4 different keywords present in the text. could anyone help me with it. Thanks in advance.

#include <stdio.h>

int main()
{
 FILE *fp;
 char filename[100];
 char ch;
 int linecount, wordcount;


 linecount = 0;
 wordcount = 0;


  printf("Enter a filename :");
  gets(filename);


   fp = fopen(filename,"r");


   if ( fp )
   {

	   while ((ch=getc(fp)) != EOF) {


		   if (ch == ' ' || ch == '\n') { ++wordcount; }

      if (ch == '\n') { ++linecount; }

	   }

	   if (wordcount > 0) {
		++linecount;
		++wordcount;
	   }
    }
   else
      {
         printf("failed to open the file\n");
        }

    printf("Lines : %d \n", linecount);
    printf("Words : %d \n", wordcount);

return(0);
}