C program to calculate number of words in a string

Write a C program to calculate the number of words in a string.

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

  int main() {
        char str[512];
        int i = 0, words = 0, n;

        /* get the input string from the user */
        printf("Enter your input string:");
        fgets(str, 512, stdin);
        str[strlen(str) - 1] = '\0';

        /* 
         * if the 1st character in input string is 
         * null, then number of words is zero
         */
        if (str[0] == '\0') {
                printf("No of words in the given string is 0\n");
                return 0;
        }

        /* calculate the number of words */
        while (str[i] != '\0') {
                if (str[i] == ' ')
                        words++;
                i++;
        }

        /* print the number of words */
        printf("Number of words in the given string is %d\n", words + 1);
        return 0;
  }

  Output:

  jp@jp-VirtualBox:~/$ ./a.out
  Enter your input string:Hello Friend!! How Are You?
  Number of words in the given string is 5