C program to count the number of uppercase and lowercase characters in a string

Write a C program to count the number of uppercase and lowercase characters in a string.

  #include <stdio.h>
  #include <string.h>

  int main() {
        char string[256];
        int upper, lower, i;

        upper = lower = i = 0;

        /* get the input strin from the user */
        printf("Enter your input string:");
        fgets(string, 256, stdin);
        string[strlen(string) - 1] = '\0';

        /* count the number of upper and lower case characters */
        while (string[i] != '\0') {

                /* number of upper case characters */
                if (string[i] >= 'A' && string[i] <= 'Z') {
                        upper++;
                } else if (string[i] >= 'a' && string[i] <= 'z') {
                        /* no of lowercase characters */
                        lower++;
                }
                i++;
        }

        /* print the result */
        printf("Number of uppercase characters: %d\n", upper);
        printf("Number of lowercase characters: %d\n", lower);
        return 0;
  }

  Output:

  jp@jp-VirtualBox:~/$ ./a.out
  Enter your input string:UPPERCASE lowercase
  Number of uppercase characters: 9
  Number of lowercase characters: 9