std::ctype::is(3)

okay bestie, welcome to std::ctype::is(3) from the C++ Standard Libary manual. It's giving "character classification, but make it a C++ standard library specialization" and honestly? iconic 💅

💖 NAME 💖

• std::ctype::is — std::ctype::is (yes bestie, the name section is literally the same thing twice; no notes 💖)

✨ Synopsis ✨

Defined in header <locale>

bool is( mask m, char c ) const;

(1)

const char* is( const char* low, const char* high, mask* vec ) const;

(2)

1. Checks if the character c is classified by the mask m according to the classification table returned by the member function table(). Effectively calculates table()[(unsigned char)c] & m.
2. For every character in the character array [low, high), reads its full classification mask from the classification table returned by the member function table() (that is, evaluates table()[(unsigned char)*p] and stores it in the corresponding element of the array pointed to by vec.

If (unsigned char)c >= std::ctype<char>::table_size, then an implementation-defined value is substituted instead of table()[(unsigned char)c], possibly different for different values of c.

🫶 Parameters 🫶

• c — character to classify
• m — mask to use for classifying a single character
• low — pointer to the first character in an array of characters to classify
• high — one past the end pointer for the array of characters to classify
• vec — pointer to the first element of the array of masks to fill

🌈 Return value 🌈

1. true if c is classified by m in table(), false otherwise.
2. high

💭 Notes 💭

Unlike the primary template std::ctype, this specialization does not perform a virtual function call when classifying characters. To customize the behavior, a derived class may provide a non-default classification table to the base class constructor. slay ✨

🎀 Example 🎀

This section is incomplete Reason: no example

the page said it, not me 😭

🧚 Defect reports 🧚

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

• DR: LWG 28
• Applied to: C++98
• Behavior as published: overload (2) copied the values from vec into table(), which is the reverse of the intended behavior
• Correct behavior: corrected

👀 See also 👀

• do_is — classifies a character or a character sequence
• [virtual] — virtual protected member function of std::ctype<CharT>

🏷️ Category 🏷️

• * Todo no example

---

That's the whole page, bestie 🫶 big source/version/date kiss from http://cppreference.com, 2024.06.10, on std::ctype::is(3). 💖