如何使用标准库将字符串转换为大写？

let str = "hello world";
let upperCaseStr = str.toUpperCase();
console.log(upperCaseStr);  // 输出 "HELLO WORLD"

str = "hello world"
upper_case_str = str.upper()
print(upper_case_str)  # 输出 "HELLO WORLD"

String str = "hello world";
String upperCaseStr = str.toUpperCase();
System.out.println(upperCaseStr);  // 输出 "HELLO WORLD"

#include <iostream>
#include <algorithm>
#include <string>

int main() {
    std::string str = "hello world";
    std::transform(str.begin(), str.end(), str.begin(), ::toupper);
    std::cout << str << std::endl;  // 输出 "HELLO WORLD"
    return 0;
}