Question

If I have a string x='wow' in Python, I can concatenate this string with itself using the __add__ function, like so:

x='wow'  
x.__add__(x)  
'wowwow'

How can I do this in C++?

Answer 1

Semantically, the equivalent of your python code would be something like

std::string x = "wow";
x + x;

i.e. create a temporary string which is the concatenation of x with x and throw away the result. To append to x you would do the following:

std::string x = "wow";
x += x;

Note the double quotes ". Unlike python, in C++, single quotes are for single characters, and double-quotes for null terminated string literals.

See this std::string reference.

By the way, in Python you wouldn’t usually call the __add__() method. You would use the equivalent syntax to the first C++ example:

x = 'wow'
x + x

The __add__() method is just the python way of providing a “plus” operator for a class.