Calculator v1

[Gaijin]

The difference between using std::endl and "\n" to end a line is that std::endl will also flush the buffer to the screen (ie, is the same as doing << "\n" << std::flush();). Useful if you want to make sure the user will always see what you are pushing into the buffer when you end the line.

+

Code:

while(option<1 || option>4);
while(option!=4)

You see that, those two loops are almost the same.
You could easy put that all in one loop

Code:

while(option > 4) {
    switch(option) {
        // cases 1 to 4
        // case 1:
        // do();
        // break;
        default:
            return 1;
    }
}

The default part would execute on every number that's not in the range from 1-4, so no need for option < 1 and the second while loop.
So you can use the default to call the selection menu again.