Editing C syntax (section)

====Character constants====
Individual character constants are single-quoted, e.g. {{code|'A'}}, and have type {{code|int}} (in C++, {{code|char}}). The difference is that {{code|"A"}} represents a null-terminated array of two characters, 'A' and '\0', whereas {{code|'A'}} directly represents the character value (65 if ASCII is used). The same backslash-escapes are supported as for strings, except that (of course) {{code|"}} can validly be used as a character without being escaped, whereas {{code|'}} must now be escaped.

A character constant cannot be empty (i.e. {{code|''}} is invalid syntax), although a string may be (it still has the null terminating character). Multi-character constants (e.g. {{code|'xy'}}) are valid, although rarely useful — they let one store several characters in an integer (e.g. 4 ASCII characters can fit in a 32-bit integer, 8 in a 64-bit one). Since the order in which the characters are packed into an {{code|int}} is not specified (left to the implementation to define), portable use of multi-character constants is difficult.

Nevertheless, in situations limited to a specific platform and the compiler implementation, multicharacter constants do find their use in specifying signatures. One common use case is the [[OSType]], where the combination of Classic Mac OS compilers and its inherent big-endianness means that bytes in the integer appear in the exact order of characters defined in the literal. The definition by popular "implementations" are in fact consistent: in GCC, Clang, and [[Visual C++]], {{code|'1234'}} yields <code>0x3'''1'''3'''2'''3'''3'''3'''4'''</code> under ASCII.<ref>{{cite web |title=The C Preprocessor: Implementation-defined behavior |url=https://gcc.gnu.org/onlinedocs/cpp/Implementation-defined-behavior.html |website=gcc.gnu.org}}</ref><ref>{{cite web |title=String and character literals (C++) |url=https://docs.microsoft.com/en-us/cpp/cpp/string-and-character-literals-cpp?view=vs-2019#code-try-2 |website=Visual C++ 19 Documentation |access-date=20 November 2019 |language=en-us}}</ref>

Like string literals, character constants can also be modified by prefixes, for example {{code|L'A'}} has type {{code|wchar_t}} and represents the character value of "A" in the wide character encoding.