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std::wstring_convert::from_bytes

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< cpp‎ | locale‎ | wstring convert
Revision as of 18:25, 2 November 2012 by P12bot (Talk | contribs)

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<td>
Defined in header <locale>
</td>

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<td >
wide_string from_bytes( char byte );
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<td > (1) </td> <td class="t-dcl-nopad"> </td> </tr> <tr class="t-dcl-sep"><td></td><td></td><td></td></tr>

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<td >
wide_string from_bytes( const char* ptr );
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<td > (2) </td> <td class="t-dcl-nopad"> </td> </tr> <tr class="t-dcl-sep"><td></td><td></td><td></td></tr>

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<td >
wide_string from_bytes( const byte_string& str );
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<td > (3) </td> <td class="t-dcl-nopad"> </td> </tr> <tr class="t-dcl-sep"><td></td><td></td><td></td></tr>

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wide_string from_bytes( const char* first, const char* last);
</td>

<td > (4) </td> <td class="t-dcl-nopad"> </td> </tr> Template:ddcl list end

Performs multibyte to wide conversion, using the codecvt facet supplied at construction.

1) Converts byte as if it was a string of length 1 to wide_string

2) Converts the null-terminated multibyte character sequence beginning at the character pointed to by ptr to wide_string

3) Converts the narrow string str to wide_string.

4) Converts the narrow multibyte character sequence [first, last) to wide_string

In all cases, the conversion begins in initial shift state, unless non-initial starting state was provided to this wstring_convert constructor. The number of characters converted and the final value of the conversion state are remembered and can be accessed with Template:rlpf and Template:rlpf

Contents

Return value

A wide_string object containing the results of multibyte to wide conversion. If the conversion failed and there was a user-supplied wide-error string provided to the constructor of this wstring_convert, returns that wide-error string.

Exceptions

If this wstring_convert object was constructed without a user-supplied wide-error string, throws std::range_error on conversion failure.

Example

#include <iostream>
#include <string>
#include <locale>
#include <codecvt>
int main()
{
    std::string utf8 =  u8"z\u00df\u6c34\U0001d10b"; // or u8"zß水𝄋"
                        // or "\x7a\xc3\x9f\xe6\xb0\xb4\xf0\x9d\x84\x8b";
 
    // the UTF-8 / UTF-16 standard conversion facet
    std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t> utf16conv;
    std::u16string utf16 = utf16conv.from_bytes(utf8.data());
    std::cout << "UTF16 conversion produced " << utf16.size() << " code points:\n";
    for(char16_t c : utf16)
        std::cout << std::hex << std::showbase << c << '\n';
 
    // the UTF-8 / UTF-32 standard conversion facet
    std::wstring_convert<std::codecvt_utf8<char32_t>, char32_t> utf32conv;
    std::u32string utf32 = utf32conv.from_bytes(utf8);
    std::cout << "UTF32 conversion produced " << std::dec << utf32.size() << " code points:\n";
    for(char32_t c : utf32)
        std::cout << std::hex << std::showbase << c << '\n';
}

Output:

UTF16 conversion produced 5 code points:
0x7a
0xdf
0x6c34
0xd834
0xdd0b
UTF32 conversion produced 4 code points:
0x7a
0xdf
0x6c34
0x1d10b

See also

Template:cpp/locale/wstring convert/dcl list to bytesTemplate:cpp/string/multibyte/dcl list mbsrtowcsTemplate:cpp/locale/codecvt/dcl list do in