Struct char array member initialization in C++

Question

I'm trying to understand struct initialization in C++, in special char array member:

struct S {
    int x;
    char str[16];
};

// (1) This would be the desired way: simple and compact, but doesn't work
S s1={.x=12, .str = "Hello2"};

// (2) Instead, this appears the correct way to do, but it is ugly and cumbersome for bigger strings
S s2={.x=25, .str = {'H','e','l','l','o', '1'}};

// (3) This works too, easy to type, but uses 2 lines and a additional function (strcpy)
S s3={.x=12};
strcpy(s3.str, "Hello3");

Why doesn't modern C ++ accept the (1) form? It would be the most elegant, concise and practical way. Considering (2) and (3), is there a better way to do this?

EDIT 1: The code I choose to put in this question has been oversimplified. My actual code involves a char[] member within a union within a structure. Then, std::string is not an option.

The standard way to handle strings in C++ is to use std::string. What is the actual problem this structure is supposed to solve? Why do you need a fixed-size array? And if you can't get rid of the array, why not create a constructor which initializes the array? — Some programmer dude
– Some programmer dude, Commented May 6, 2020 at 16:18
"Why doesn't modern C ++ accept the (1) form?" Because modern C++ (and old C++) uses std::string instead of char arrays. — Yksisarvinen
– Yksisarvinen, Commented May 6, 2020 at 16:20
Your (1) code does work in clang-cl and MSVC (the latter with /std:c++latest - in order to use the designated initializers). — Adrian Mole
– Adrian Mole, Commented May 6, 2020 at 16:21
The code I chose to put in this question has been oversimplified. My actual code involves a char[] member within a union within a structure. I can't put std::string inside union. — Berk7871
– Berk7871, Commented May 6, 2020 at 16:42

bruno · Accepted Answer · 2020-05-06 16:29:06Z

1

just replace

S s1={.x=12, .str = "Hello2"};

by the 'C' initialization form

S s1={12, "Hello2"};

or as said in remarks use a std::string which is a most elegant, concise and practical way than an array of char for a string, and you will able to use the 'C++' initialization form you wanted

edited May 6, 2020 at 16:29

answered May 6, 2020 at 16:23

bruno

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3 Comments

Berk7871 Over a year ago

But It requires to follow the order of the member fields. It is possible to use designators (member names) in some way?

bruno Over a year ago

@Berk7871 yes you have to take care of the order as in C, no you cannot use designators because only the C++ form allows that

Berk7871 Over a year ago

Ok. I am curious as to why the C ++ Committee did not include this simple feature (allowing the use of designators to initialize a char[] from a literal string) in the language.

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