C program to find frequency of characters in a string

C programming code

#include <stdio.h>
#include <string.h>
 
int main()
{
   char string[100];
   int c = 0, count[26] = {0};
 
   printf("Enter a string\n");
   gets(string);
 
   while ( string[c] != '\0' )
   {
      /* Considering characters from 'a' to 'z' only */
 
      if ( string[c] >= 'a' && string[c] <= 'z' ) 
         count[string[c]-'a']++;
 
      c++;
   }
 
   for ( c = 0 ; c < 26 ; c++ )
   {
      if( count[c] != 0 )
         printf("%c occurs %d times in the entered string.\n",c+'a',count[c]);
   }
 
   return 0;
}

Explanation of "count[string[c]-'a']++", suppose input string begins with 'a' so c is 0 initially and string[0] = 'a' and string[0]-'a' = 0 and we increment count[0] i.e. a has occurred one time and repeat this till complete string is scanned.

Download Character frequency program.

Output of program:

Did you notice that string in the output of program contains every alphabet at least once.