นับคำ

#include <ctype.h>
#include <stdio.h>
int main(void) {
    const char *text = "C and C++ examples"; int words = 0, inside = 0;
    // Count transitions from whitespace into a word.
    for (; *text; ++text) { if (isspace((unsigned char)*text)) inside = 0; else if (!inside) { ++words; inside = 1; } }
    printf("words=%d\n", words);
}

#include <iostream>
#include <sstream>
#include <string>
int main() {
    std::istringstream input("C and C++ examples"); std::string word; int words = 0;
    // Formatted extraction skips whitespace and returns one word.
    while (input >> word) ++words;
    std::cout << "words=" << words << '\n';
}