[c++] 'cout' was not declared in this scope

I have a C++ program:

test.cpp

#include<iostream>

int main()
{
    char t = 'f';
    char *t1;
    char **t2;
    cout<<t;    //this causes an error, cout was not declared in this scope
    return 0;
}

I get the error:

'cout' was not declared in this scope

Why?

Use std::cout, since cout is defined within the std namespace. Alternatively, add a using std::cout; directive.