Question

搜索与平台和第三方库无关的迭代UTF-8字符串或将其拆分为UTF-8符号数组的方法。

请发布代码段。

解决： C++ iterate or split UTF-8 string into array of symbols?

Answer 1

如果我理解正确，听起来你想要找到每个UTF-8字符的开头。如果是这样，那么解析它们就相当简单（解释它们是另一回事）。但RFC：

明确定义了涉及多少八位字节的定义

Char. number range  |        UTF-8 octet sequence
   (hexadecimal)    |              (binary)
--------------------+---------------------------------------------
0000 0000-0000 007F | 0xxxxxxx
0000 0080-0000 07FF | 110xxxxx 10xxxxxx
0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx

例如，如果lb具有UTF-8字符的第一个八位字节，我认为以下内容将决定所涉及的八位字节数。

unsigned char lb;

if (( lb & 0x80 ) == 0 )          // lead bit is zero, must be a single ascii
   printf( "1 octet\n" );
else if (( lb & 0xE0 ) == 0xC0 )  // 110x xxxx
   printf( "2 octets\n" );
else if (( lb & 0xF0 ) == 0xE0 ) // 1110 xxxx
   printf( "3 octets\n" );
else if (( lb & 0xF8 ) == 0xF0 ) // 1111 0xxx
   printf( "4 octets\n" );
else
   printf( "Unrecognized lead byte (%02x)\n", lb );

但最终，如果在另一篇文章中建议您使用现有库会更好。上面的代码可能会根据八位字节对字符进行分类，但是一旦完成，它就无法帮助它们做任何事情。

Answer 2

使用与平台无关的小型UTF8 CPP库解决：

    char* str = (char*)text.c_str();    // utf-8 string
    char* str_i = str;                  // string iterator
    char* end = str+strlen(str)+1;      // end iterator

    unsigned char[5] symbol = {0,0,0,0,0};

    do
    {
        uint32_t code = utf8::next(str_i, end); // get 32 bit code of a utf-8 symbol
        if (code == 0)
            continue;

        utf8::append(code, symbol); // initialize array `symbol`
    }
    while ( str_i < end );

Answer 3

UTF8 CPP正是您想要的

Answer 4

尝试ICU Library。

Answer 5

脱下袖口：

// Return length of s converted. On success return should equal s.length().
// On error return points to the character where decoding failed.
// Remember to check the success flag since decoding errors could occur at
// the end of the string
int convert(std::vector<int>& u, const std::string& s, bool& success) {
    success = false;
    int cp = 0;
    int runlen = 0;
    for (std::string::const_iterator it = s.begin(), end = s.end(); it != end; ++it) {
        int ch = static_cast<unsigned char>(*it);
        if (runlen > 0) {
            if ((ch & 0xc0 != 0x80) || cp == 0) return it-s.begin();
            cp = (cp << 6) + (ch & 0x3f);
            if (--runlen == 0) {
                u.push_back(cp);
                cp = 0;
            }
        }
        else if (cp == 0) {
            if (ch < 0x80)      { u.push_back(ch); }
            else if (ch > 0xf8) return it-s.begin();
            else if (ch > 0xf0) { cp = ch & 7; runlen = 3; }
            else if (ch > 0xe0) { cp = ch & 0xf; runlen = 2; }
            else if (ch > 0xc0) { cp = ch & 0x1f; runlen = 1; }
            else return it-s.begin(); // stop on error
        }
        else return it-s.begin();
    }
    success = runlen == 0; // verify we are between codepoints
    return s.length();
}

C ++将UTF-8字符串迭代或拆分为符号数组？

5 个答案: