6-1 how many words are needed to form a sentence?

This question requests to realize a function , Count the number of words in a string .

Function interface definition ：

int fun ( char *s );

Sample referee test procedure ：

 Here is an example of a function being called for testing . for example ：
#include <stdio.h>

int  fun ( char *str );

int main()
{

 char str[20];

  gets(str);

  printf("%d",fun(str));

  return 0;

}

/*  Please fill in the answer here  */

sample input ：

how are you

sample output ：

3

int  fun ( char *s )
{
    int count=0;
    int i=0;
    while(s[i]){
        if(s[i]==' ')
            count++;
         i++;
    }
    return count+1;
}