在c++中使用循环打印字符串的方法有哪些？

#include <iostream>
#include <string>

int main() {
    std::string str = "Hello World!";
    for (int i = 0; i < str.length(); i++) {
        std::cout << str[i];
    }
    return 0;
}

#include <iostream>
#include <string>

int main() {
    std::string str = "Hello World!";
    int i = 0;
    while (i < str.length()) {
        std::cout << str[i];
        i++;
    }
    return 0;
}

#include <iostream>
#include <string>

int main() {
    std::string str = "Hello World!";
    for (char ch : str) {
        std::cout << ch;
    }
    return 0;
}