My calculator program keeps crashing at the end

[GCDEF]

I started learning like two days ago... It was the only way I could think of this working. And so it can respond with "Nice, what are you (adding/subtracting/multiplying/dividing) 5 by?"

Following your design, you could have a GetAandC() function. After you find out which operation the user wants, set up an if or switch statement like

if(b == "*")
    Multiply();
else
if(b == "/")
    Divide();
...

Also, you really need to forget you've even heard of the goto statment. NO respectable C++ programmer would use it. Learn how to use while and for loops to repeat operations.

Also, when posting, please use CODE tags to preserve formatting.