glibc 中 fputwc()、putwc() 和 putwchar() 定义不一致

Why fputwc(), putwc() and putwchar()接受类型参数wchar_t代替wint_t？ 这与相应的非宽字符函数相矛盾fputc(), putc() and putchar(), 这需要int, not char.

那是因为wchar_t需要持有WEOF值和char不需要持有EOF value.

For char, the fputc(), putc() and putchar() functions need to accept values which can hold both values in the unsigned char and EOF range, where EOF can be a negative number so a int is required to hold them both.¹

Whereas wchar_t itself is required to hold a WEOF character as well as the biggest locale.² WEOF represents a value which fits inside wchar_t but doesn't overlap with any locale.³

This is made more confusing because of the the names of char and wchar_t, you shouldn't see wchar_t as a char but more as a int which size isn't dependent on the architecture but on the size of the biggest locale (and on the value of WEOF).⁴

¹ Why putchar, toupper, tolower, etc. take a int instead of a char?

² Quoting ISO/IEC 9899:201x 7.19.2:

WEOF它扩展为类型的常量表达式wint_t其值不对应于扩展字符集的任何成员。本子条款中的几个函数接受（并返回）它以指示文件结尾，也就是说，不再有来自 溪流。它还用作不对应于扩展字符集的任何成员的宽字符值。

³ Quoting your link:

宏观WEOF计算结果为类型的常量表达式wint_t 其值不同于扩展字符集的任何成员。

⁴ Quoting C++ Reference:

wchar_t其值范围可以表示受支持的语言环境中指定的最大扩展字符集的所有成员的不同代码的类型。

In c++, wchar_t是一个独特的基本类型（因此它没有在<cwchar>也没有任何其他标头）。

In c， 这是一个typedef属于整数类型。