About std:cout in C++

Question

Is there an error in this code:

#include <iostream>
using namespace std;

int main()
{
    std:cout << "hello" "\n";
}

GCC detects no error but std:cout does not seem standard.

Answer 1

There's no error. I could rewrite your code to make it clearer:

#include <iostream>
using namespace std;

int main()
{
std:
    cout << "hello" "\n";
}

You created a label named std. cout is used unqualified, which is okay since you have the using-directive for std above it. And you can concatenate string literals by writing them next to each other as you did. This is perfectly well-formed code that prints "hello" followed by a newline.