C++ mbrtowc()用法及代码示例

C /C++中的mbrtowc()函数将多字节序列转换为宽字符。此函数返回多字节字符的字节长度。 s指向的多字节字符将转换为wchar_t类型的值，并存储在pwc指向的位置。如果s指向空字符，则该函数将移位状态复位并在将宽的空字符存储在pwc之后返回零。

用法:

size_t mbrtowc (wchar_t* pwc, const char* pmb, size_t max, mbstate_t* ps)

参数：该函数接受四个参数，如下所述：

pwc :指向将写入宽字符的位置的指针
s :指向用作输入的多字节字符串的指针
n :可以检查的s中的字节数限制
ps :指向解释多字节字符串时使用的转换状态的指针

返回值：该函数返回四个值，如下所示：

如果为null宽字符或pmb为null指针，则该函数返回0
从s成功转换的多字节字符的字节数[1…n]
如果pmb的最大前几个字符形成不完整的多字节字符，则该函数返回length-2
否则，函数返回length-1并将errno设置为EILSEQ

注意：可能返回的值都不小于零。

以下示例程序旨在说明上述函数：
示例1:

// C++ program to illustrate 
// mbrtowc() function 
#include <bits/stdc++.h> 
using namespace std; 
  
// Function to convert multibyte 
// sequence to wide character 
void print_(const char* s) 
{ 
    // initial state 
    mbstate_t ps = mbstate_t(); 
  
    // length of the string 
    int length = strlen(s); 
  
    const char* n = s + length; 
    int len; 
    wchar_t pwc; 
  
    // printing each bytes 
    while ((len = mbrtowc(&pwc, s, n - s, &ps)) > 0) { 
        wcout << "Next " << len <<  
        " bytes are the character " << pwc << '\n'; 
        s += len; 
    } 
} 
  
// Driver code 
int main() 
{ 
    setlocale(LC_ALL, "en_US.utf8"); 
  
    // UTF-8 narrow multibyte encoding 
    const char* str = u8"z\u00df\u6c34\U0001d10b"; 
  
    print_(str); 
}

输出：

Next 1 bytes are the character z
Next 2 bytes are the character Ã?
Next 3 bytes are the character æ°´
Next 4 bytes are the character ð??

示例2:

// C++ program to illustrate 
// mbrtowc() function 
// with different UTF-8 characters 
#include <bits/stdc++.h> 
using namespace std; 
  
// Function to convert multibyte 
// sequence to wide character 
void print_(const char* s) 
{ 
    // initial state 
    mbstate_t ps = mbstate_t(); 
  
    // length of the string 
    int length = strlen(s); 
  
    const char* n = s + length; 
    int len; 
    wchar_t pwc; 
  
    // printing each bytes 
    while ((len = mbrtowc(&pwc, s, n - s, &ps)) > 0) { 
        wcout << "Next " << len <<  
        " bytes are the character " << pwc << '\n'; 
        s += len; 
    } 
} 
  
// Driver code 
int main() 
{ 
    setlocale(LC_ALL, "en_US.utf8"); 
  
    // UTF-8 narrow multibyte encoding 
    const char* str = u8"\xE2\x88\x83y\xE2\x88\x80x\xC2\xAC"; 
  
    print_(str); 
}

输出：

Next 3 bytes are the character â??
Next 1 bytes are the character y
Next 3 bytes are the character â??
Next 1 bytes are the character x
Next 2 bytes are the character Â¬

相关用法

注：本文由纯净天空筛选整理自AmanSrivastava1大神的英文原创作品 mbrtowc() function in C/C++。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。