12月13日是什么纪念日
From cppreference.com
| Defined in header <wctype.h>
|
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| wint_t towlower( wint_t wc ); |
(since C95) | |
Converts the given wide character to lowercase, if possible.
Contents |
[edit] Parameters
| wc | - | wide character to be converted |
[edit] Return value
Lowercase version of wc or unmodified wc if no lowercase version is listed in the current C locale.
[edit] Notes
Only 1:1 character mapping can be performed by this function, e.g. the Greek uppercase letter 'Σ' has two lowercase forms, depending on the position in a word: 'σ' and '?'. A call to towlower cannot be used to obtain the correct lowercase form in this case.
ISO 30112 specifies which pairs of Unicode characters are included in this mapping.
[edit] Example
Run this code
#include <locale.h> #include <stdio.h> #include <wchar.h> #include <wctype.h> int main(void) { wchar_t wc = L'\u0190'; // Latin capital open E ('?') printf("in the default locale, towlower(%#x) = %#x\n", wc, towlower(wc)); setlocale(LC_ALL, "en_US.utf8"); printf("in Unicode locale, towlower(%#x) = %#x\n", wc, towlower(wc)); }
Output:
in the default locale, towlower(0x190) = 0x190 in Unicode locale, towlower(0x190) = 0x25b
[edit] References
- C23 standard (ISO/IEC 9899:2024):
- 7.30.3.1.1 The towlower function (p: TBD)
- C17 standard (ISO/IEC 9899:2018):
- 7.30.3.1.1 The towlower function (p: TBD)
- C11 standard (ISO/IEC 9899:2011):
- 7.30.3.1.1 The towlower function (p: 453)
- C99 standard (ISO/IEC 9899:1999):
- 7.25.3.1.1 The towlower function (p: 399)
[edit] See also
| (C95) |
converts a wide character to uppercase (function) |
| converts a character to lowercase (function) | |
| C++ documentation for towlower
| |
