Does it make a difference in how you initialize a string in modern C++?

Question

Is there a difference or is just a matter of preference? I'm a beginner to c++ and it bothers me that I am not confident that I'm choosing the right way to initialize a string value.

If I were to just choose one way which works for the vast majority of use cases, which would it be?

// Initializing from a literal. std::string s1{"hello"}; std::string s2("there"); std::string s3 = {"what"}; std::string s4 = "is"; // Initializing from another string object. std::string s5{s1}; std::string s6(s1); std::string s7 = s1; std::string s8 = {s1};

PS: Apologies if this question in it's entirety has been asked before, I couldn't find it anywhere and would appreciate it if someone could link to it here.

I recommend rewording your question to ask about the general technical differences between those different ways of initializing a string, as asking for "the right way" might be closed as off-topic (primarily opinion based). — Max
– Max, Commented Mar 31, 2019 at 2:52
I expect modern C++ compilers to generate identical code for all of the logically equivalent alternatives. So this is purely a matter of personal opinion and preferences. — Sam Varshavchik
– Sam Varshavchik, Commented Mar 31, 2019 at 2:52
@SamVarshavchik - Thanks, would you state it as a fact that all compilers would treat them as equivalent? Or are there certain situations where one is preferred over the other? It's a bit strange that c++ allows so many ways to initialize a string, there must be some reasoning behind it other than backwards compatibility? — Plasty Grove
– Plasty Grove, Commented Mar 31, 2019 at 4:01

Alecto · Accepted Answer · 2019-03-31 03:30:23Z

For strings in particular, you will always be able to use all of the above, and it's really just a matter of personal preference.

I personally prefer

auto s1 = std::string(); //Initialize empty string auto s2 = std::string("Hello, world"); // Initialize string containing "Hello, world" auto s3 = s2; //Make a copy of s2 auto s4 = std::move(s3); //Move s3 into s4

And the reason I prefer that is because it works on all types. You can't forget to initialize something if you use auto:

int i; //Oops, forgot to initialize i, because i is a primitive

Versus:

auto i = 0; //i set to 0 auto i2 = size_t(0); //i2 is a size, and set to 0 auto i3; //Error: forgot to initialize

The important thing is to remain consistent throughout the codebase.

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