Question

I have a small program that uses “trying to use” #include <queue>. I use Ubuntu OS but it says:

fatal error: queue: No such file or directory

Any ideas why, or what I need to do to make it work?

#include <queue>
using namespace std; 


int main()
{
    queue<int> Q;
    Q.push( 1 );
    Q.push( 2 );
    Q.push( 3 );
    cout << Q.front();
    Q.pop();
    cout << Q.front();
    Q.pop();
    cout << Q.front();
    Q.pop(); 

    return 0;
}

Answer 1

You are compiling your C++ program (which you saved with a .c extension) with a C compiler.

This won’t work, since you’re using the C++ STL (and namespace std).

Compile using g++ instead:

g++ queuetest.cpp -o queuetest

See the docs for compiling C++. Consider changing your extension to .cpp as well.

You’ll also want to #include <iostream> for cout.