将“:：”替换为“”。‘在C++中创建歧义？

#include <iostream>

int main() {
    std::cout << "Hello, World!" << std::endl;
    return 0;
}

#include <iostream>

int main() {
    std cout << "Hello, World!" << std endl;
    return 0;
}

#include <iostream>

using std::cout;
using std::endl;

int main() {
    cout << "Hello, World!" << endl;
    return 0;
}

#include <iostream>

using namespace std;

int main() {
    cout << "Hello, World!" << endl;
    return 0;
}