返回类型char*的成员函数在while循环后返回包含不同字符串的地址

#include <iostream>
using namespace std;

class MyClass {
public:
    char* getString() {
        char* str;
        int i = 0;
        while (i < 3) {
            if (i == 0) {
                str = "Hello";
            } else if (i == 1) {
                str = "World";
            } else {
                str = "!";
            }
            i++;
        }
        return str;
    }
};

int main() {
    MyClass obj;
    char* result = obj.getString();
    cout << result << endl;
    return 0;
}