Difference between revisions of "cpp/string/multibyte/wctob"
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{{cpp/title|wctob}} | {{cpp/title|wctob}} | ||
{{cpp/string/multibyte/navbar}} | {{cpp/string/multibyte/navbar}} | ||
| − | {{ddcl | header=cwchar | | + | {{ddcl|header=cwchar| |
int wctob( std::wint_t c ); | int wctob( std::wint_t c ); | ||
}} | }} | ||
| − | Narrows a wide character {{ | + | Narrows a wide character {{c|c}} if its multibyte character equivalent in the initial shift state is a single byte. |
This is typically possible for the characters from the ASCII character set, since most multibyte encodings (such as UTF-8) use single bytes to encode those characters. | This is typically possible for the characters from the ASCII character set, since most multibyte encodings (such as UTF-8) use single bytes to encode those characters. | ||
| Line 11: | Line 11: | ||
===Parameters=== | ===Parameters=== | ||
{{par begin}} | {{par begin}} | ||
| − | {{par | c | wide character to narrow}} | + | {{par|c|wide character to narrow}} |
{{par end}} | {{par end}} | ||
===Return value=== | ===Return value=== | ||
| − | {{lc|EOF}} if {{ | + | {{lc|EOF}} if {{c|c}} does not represent a multibyte character with length {{c|1}} in initial shift state. |
| − | Otherwise, the single-byte representation of {{ | + | Otherwise, the single-byte representation of {{c|c}} as {{c|unsigned char}} converted to {{c|int}}. |
===Example=== | ===Example=== | ||
{{example | {{example | ||
| − | + | |code= | |
| − | + | ||
#include <clocale> | #include <clocale> | ||
#include <cwchar> | #include <cwchar> | ||
| Line 30: | Line 29: | ||
{ | { | ||
int cn = std::wctob(c); | int cn = std::wctob(c); | ||
| − | if(cn != EOF) | + | if (cn != EOF) |
| − | std::cout << '\'' << c << "' narrowed to " << +cn << '\n'; | + | std::cout << '\'' << int(c) << "' narrowed to " << +cn << '\n'; |
else | else | ||
| − | std::cout << '\'' << c << "' could not be narrowed\n"; | + | std::cout << '\'' << int(c) << "' could not be narrowed\n"; |
} | } | ||
| Line 48: | Line 47: | ||
try_narrowing(L'๛'); | try_narrowing(L'๛'); | ||
} | } | ||
| − | + | |output= | |
In Thai UTF-8 locale: | In Thai UTF-8 locale: | ||
'0x61' narrowed to 0x61 | '0x61' narrowed to 0x61 | ||
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===See also=== | ===See also=== | ||
{{dsc begin}} | {{dsc begin}} | ||
| − | {{dsc inc | cpp/string/multibyte/dsc btowc}} | + | {{dsc inc|cpp/string/multibyte/dsc btowc}} |
| − | {{dsc inc | cpp/io/basic_ios/dsc narrow}} | + | {{dsc inc|cpp/io/basic_ios/dsc narrow}} |
| − | {{dsc inc | cpp/locale/ctype/dsc narrow}} | + | {{dsc inc|cpp/locale/ctype/dsc narrow}} |
| − | {{dsc see c | c/string/multibyte/wctob}} | + | {{dsc see c|c/string/multibyte/wctob}} |
{{dsc end}} | {{dsc end}} | ||
| − | + | {{langlinks|de|es|fr|it|ja|pt|ru|zh}} | |
| − | + | ||
| − | + | ||
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Latest revision as of 22:51, 9 June 2023
| Defined in header <cwchar>
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| int wctob( std::wint_t c ); |
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Narrows a wide character c if its multibyte character equivalent in the initial shift state is a single byte.
This is typically possible for the characters from the ASCII character set, since most multibyte encodings (such as UTF-8) use single bytes to encode those characters.
Contents |
[edit] Parameters
| c | - | wide character to narrow |
[edit] Return value
EOF if c does not represent a multibyte character with length 1 in initial shift state.
Otherwise, the single-byte representation of c as unsigned char converted to int.
[edit] Example
Run this code
#include <clocale> #include <cwchar> #include <iostream> void try_narrowing(wchar_t c) { int cn = std::wctob(c); if (cn != EOF) std::cout << '\'' << int(c) << "' narrowed to " << +cn << '\n'; else std::cout << '\'' << int(c) << "' could not be narrowed\n"; } int main() { std::setlocale(LC_ALL, "th_TH.utf8"); std::cout << std::hex << std::showbase << "In Thai UTF-8 locale:\n"; try_narrowing(L'a'); try_narrowing(L'๛'); std::setlocale(LC_ALL, "th_TH.tis620"); std::cout << "In Thai TIS-620 locale:\n"; try_narrowing(L'a'); try_narrowing(L'๛'); }
Output:
In Thai UTF-8 locale: '0x61' narrowed to 0x61 '0xe5b' could not be narrowed In Thai TIS-620 locale: '0x61' narrowed to 0x61 '0xe5b' narrowed to 0xfb
[edit] See also
| widens a single-byte narrow character to wide character, if possible (function) | |
| narrows characters (public member function of std::basic_ios<CharT,Traits>)
| |
invokes do_narrow (public member function of std::ctype<CharT>)
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| C documentation for wctob
| |
