btowc

将单字节字符c（重新解释为无符号字符）扩展为宽字符等效字符。

大多数多字节字符编码使用单字节代码来表示ASCII字符集中的字符。 该函数可用于将这些字符转换为wchar_t。

参数

返回值

若 c 为EOF则返回WEOF

如果（无符号字符）c在初始转换状态下是有效的单字节字符，否则为WEOF。

例

#include <stdio.h>
#include <wchar.h>
#include <locale.h>
#include <assert.h>
 
void try_widen(unsigned char c)
{
    wint_t w = btowc(c);
    if(w != WEOF)
        printf("The single-byte character %#x widens to %#x\n", c, w);
    else
        printf("The single-byte character %#x failed to widen\n", c);
}
 
int main(void)
{
    char *loc = setlocale(LC_ALL, "lt_LT.iso88594");
    assert(loc);
    printf("In Lithuanian ISO-8859-4 locale:\n");
    try_widen('A');
    try_widen('\xdf'); // German letter ß (U+00df) in ISO-8859-4
    try_widen('\xf9'); // Lithuanian letter ų (U+0173) in ISO-8859-4
 
    setlocale(LC_ALL, "lt_LT.utf8");
    printf("In Lithuanian UTF-8 locale:\n");
    try_widen('A');
    try_widen('\xdf');
    try_widen('\xf9');
}

可能的输出：

In Lithuanian ISO-8859-4 locale:
The single-byte character 0x41 widens to 0x41
The single-byte character 0xdf widens to 0xdf
The single-byte character 0xf9 widens to 0x173
In Lithuanian UTF-8 locale:
The single-byte character 0x41 widens to 0x41
The single-byte character 0xdf failed to widen
The single-byte character 0xf9 failed to widen

参考

• C11标准（ISO / IEC 9899：2011）：
  • 7.29.6.1.1 btowc函数（p：441）
• C99标准（ISO / IEC 9899：1999）：
  • 7.24.6.1.1 btowc函数（p：387）

扩展内容

| btowc的C ++文档 |