在字符串后/中保持大写

var str = "Hello World";
var upperCaseStr = str.toUpperCase();  // "HELLO WORLD"

str = "Hello World"
upper_case_str = str.upper()  # "HELLO WORLD"

String str = "Hello World";
String upperCaseStr = str.toUpperCase();  // "HELLO WORLD"

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

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

$str = "Hello World";
$upperCaseStr = strtoupper($str);  // "HELLO WORLD"