What Is a String?

01Is a string just “some text”?

A string is an ordered sequence of character data. A program can store it, inspect it, and process its elements.

02Which kind of string is commonly used in C++?

Modern C++ commonly uses std::string from the standard library.

#include <string>

std::string greeting = "Hello";

It is convenient for storing and working with a string of characters.

03How is a string related to a char array?

A C-style string is commonly stored in a character array and ends with a special null character, \0.

char text[] = "Hello";

It actually contains:

std::string is a standard-library class, so do not simply say it “is a char array.”

04What does std::string length mean?

std::string s = "Hello";
std::cout << s.size();

The result is 5.

For ordinary ASCII English text, one char is usually one byte, so this also looks like “5 characters.”

05Does one Chinese character count as one char?

Usually not in UTF-8.

std::string s = "你";

In common UTF-8 environments, s.size() usually returns 3 because this character uses 3 UTF-8 bytes.

06What operations can you do with strings?

07What is an empty string?

std::string s = "";

It is a valid string with a length of 0.

An “empty string” is not the same as “no string object was created.”