btowc

在头文件中定义
wint_t btowc（int c）;		（自C95以来）

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

C	-	单字节字符加宽

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）：

扩展内容

wctob（C95）	如果可能的话，将宽字符缩小为单字节窄字符（功能）

| btowc的C ++文档 |