What does std::string::oprator__unsigned_long do?

Question

I am new to reverse c++ program.

I met this code from r2 decompilation.

            pcVar6 = (char *)sym.imp.std::string::operator___unsigned_long
                                       (&username, (int64_t)(int32_t)(uint32_t)var_32ch,
                                        (int64_t)(int32_t)(uint32_t)var_32ch);

What does the code mean?

Thanks in advance.

Answer 1

This is an "operator overload" member function, specifically a conversion operator.

This function is called when you treat the value of the object instance (in this case, a string, as a different type (in this case, an unsigned long).

For example, if there is a function that expects an unsigned long as an argument, but you pass a string object instead, this operator member will be called to convert the string to match the type.

There are many types of conversions, such as casting:

string a = ...;
unsigned long b;

b = a; //or:
b = (unsigned long)a;

You can find more information here:

https://en.cppreference.com/w/cpp/language/cast_operator