wordCount.c

#include <string.h>
#include <stdio.h>
 
int words(const char sentence[ ])
{
    int counted = 0; // result
 
    // state:
    const char* it = sentence;
    int inword = 0;
 
    do switch(*it) {
        case '\0': 
        case ' ': case ',': case '.': case '\n':
            if (inword) { inword = 0; counted++; }
            break;
        default: inword = 1;
    } while(*it++);
 
    return counted;
}
 
int main(int argc, const char *argv[])
{
	char sentence[140];
	scanf("%139[0-9a-zA-Z ]", sentence);
    printf("%d\n", words(sentence));
}