Is C++ std::string immutable?

C++ std::string is mutable and assignment (generally) copies the string data. Java String is immutable and assignment copies a reference to the string.

Why do we use std::string in C++?

C++ has in its definition a way to represent sequence of characters as an object of class. This class is called std:: string. String class stores the characters as a sequence of bytes with a functionality of allowing access to single byte character. Take a step-up from those “Hello World” programs.

Is std::string efficient?

std::string is a far better abstraction than char * could ever be. Encapsulating pointer arithmetic is a good thing. A lot of people thought long and hard to come up with std::string . I think failing to use it for unfounded efficiency reasons is foolish.

Is std::string cow?

In C++11 std::string is not allowed to be COW.

What is immutable in C++?

In C++, an object is immutable if (1) and either (2) or (3) are met: It has no members declared mutable that are mutated by const member functions. It is declared const. const member functions do not use const_cast to remove const qualification in order to mutate any members.

What is the difference between std::string and string?

There is no functionality difference between string and std::string because they’re the same type. That said, there are times where you would prefer std::string over string .

Is std::string slow?

Any nontrivial operations (assignment, concatenation) performed on std::string typically compile into quite horrible code which is at least 3-5 times slower than same tasks would be done using standard C library (unless you’re working with _very_ long strings and time to do actual copying dominates maintenance tasks.)

Are C++ strings reference counted?

So, yes it is ref counted. Also, from the discussion here: Yes, std::string will be made non-reference counting at some point, but as a non-reference-counted string is valid in C++98 as well, one option would be to switch to a non-ref-counted string for both -std=c++98 and -std=c++11 modes.

What is mutable and immutable in C++?

A mutable object can be changed after it’s created, and an immutable object can’t. But in some other languages, like C++, strings can be mutable, and we can modify them directly: string testString(“mutable?”); testString[7] = ‘!