Template within template: why “`>>' should be `> >' within a nested template argument list”

Question

I know that when we are using template inside another template, we should write it like this:

vector > s;

and if we wr

Answer 1

Avoid this error by setting an appropriate C++ dialect. For example, with gcc 4.9 the following file does not compile with g++:

#include 
#include 

int main()
{
    using namespace std;
    vector> v; // compile error!
    return 0;
}

Let's get to the bottom of things:

#include 

int main()
{
    std::cout << __cplusplus << std::endl;
    return 0;
}

Compiled with just g++ test.cpp this code prints 199711. Although gcc 4.9 was released in 2014 the default C++ dialect is C++98 with GNU extensions. C++98 requires us to write vector >. If you like vector> more compile with -std=c++11 or -std=gnu++11.