Is there any way to optimize c++ string += operator?

Question

English is not good, but please understand.

string str;
string str_base = "user name = ";
string str_user_input;
string str_system_message;
...

str = s         


        

Answer 1

Simplistically put, there are ways to optimize this:

First, by using += instead of multiple + operations, you will avoid the creation of some temporary objects.

That is, prefer to do:

s += s1;
s += s2;
s += s3;

instead of:

s = s1 + s2 + s3;

Second, the call (the += example above) could be preceded by adding up the sizes of the strings and reserving the memory in s.

That said (I did mention it is a "simplistic" answer), here are some other considerations:

• the language designers and compiler developers already spend much much time optimizing string operations, and you are unlikely to significantly optimize your code by micro-optimizations in a function dealing with strings and user input (unless the strings are inordinately large, unless this is code on the critical path and unless you are working in a very constrained system).

• you probably got downvoted because it looks like you are focusing on the wrong problem to solve.

• optimization problems look trivial at the first look, but until you set a performance goal and a way to measure current performance, you are likely to look for optimizations in the wrong place (which it looks like you are doing now).