C run-time library function __isascii&iswascii& __toascii

Determines whether a particular character is a ASCII character.

int __isascii(
int c
);
int iswascii(
wint_t c
);

Test program:

#include "stdafx.h"
#include "ctype.h"
#include "locale.h"
#include "stdio.h"

void CheckCharAndPrint(char acChar)
{
if(__isascii(acChar))
{
printf("char %c is a ascii char.\n",acChar);
}
else
{
// 此处无法正常输出中文，没有深入研究了
printf("char %c is not a ascii char.\n",acChar);
}
}

void CheckWCharAndPrint(wchar_t awcChar)
{
if(iswascii(awcChar))
{
wprintf(L"wchar %c is a ascii char.\n",awcChar);
}
else
{
setlocale(LC_ALL,"");
wprintf(L"wchar %c is not a ascii char.\n",awcChar);
}
}

int _tmain(int argc, _TCHAR* argv[])
{
char lcC = 'a';
char lcD = '中';

CheckCharAndPrint(lcC);
CheckCharAndPrint(lcD);

wchar_t lwcC = L'a';
wchar_t lwcD = L'中';

CheckWCharAndPrint(lwcC);
CheckWCharAndPrint(lwcD);

return 0;
}

Description

__isascii is a special function because it starts with two front underscores. This is not uncommon in C language. (at least I see less)

This function should not belong to the standard library function, which is not described in the C language reference in "Tcpl", but is available in GCC. In other words, Linux can also use this function normally.

Iswascii the wide-byte version of this __isascii function, like many wide-byte versions of functions, this function belongs to Ms itself, so. Linux can not use this function, to use, you can only achieve ROM.