String literals

Description

NSConstantString or NXConstantString are the classes used by string literals.

Includes part of Cppreference’s C -> Language -> String Literals

Syntax

@" s-char-sequence "	(1)	(since )
where

s-char-sequence
zero or more characters, each of which is either a multibyte character from the source character set (excluding ("), \, and newline), or character escape, hex escape, octal escape, or universal character name (since C99) as defined in escape sequences.

1) NSConstantString literal: The type of the literal is NSConstantString* (if Foundation is being used).

Layout

GCC

struct {
    Class isa;
    char* c_string;
    unsigned int len;
}

GNUstep v2 ABI

struct {
    Class isa;
    /**
     * Flags value.  The low 16 bits are reserved for the compiler, the top 16
     * for the class implementation.  Currently, only the low 2 bits are
     * defined by the compiler.
     */
    uint32_t flags;
    /**
     * The number of UTF-16 code units in the string.
     */
    uint32_t length;
    /**
     * The number of bytes occupied by the string.
     */
    uint32_t size;
    /**
     * Storage preallocated for the hash (not initialized by the compiler).
     */
    uint32_t hash;
    /**
     * Data pointer; format described by the bottom bits of `flags`.
     */
    const char * const str;
}