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isalpha, __iscsymf, iswalpha, _ismbcalpha

Header File

ctype.h, mbstring.h

Category

Classification Routines

Prototype

int isalpha(int c);

int __iscsymf(int c);

int iswalpha(wint_t c);

int _ismbcalpha(unsigned int c);

Description

Classifies an alphabetical character.

isalpha is a macro that classifies ASCII-coded integer values by table lookup. The macro is affected by the current locale’s LC_CTYPE category. For the default C locale, c is a letter (A to Z or a to z).

You can make this macro available as a function by undefining (#undef) it.

Return Value

isalpha returns nonzero if c is a letter.

__iscsymf returns true if and only if the argument c is a letter or an underscore.

iswalpha returns nonzero if c is a wchar_t in the character set defined by the implementation.

_ismbcalpha returns true if and only if the argument c is a single-byte ASCII English letter.

Example

Copy Code

    #include <stdio.h>
    #include <ctype.h>
    int main(void)
    {
      char c = 'C';

      if (isalpha(c))
        printf("%c is alphabetical\n",c);
      else
        printf("%c is not alphabetical\n",c);
      return 0;
    }

Portability

| POSIX | Win32 | ANSI C | ANSI C++
isalpha | + | + | + | +
__iscsymf |  | + |  |
_ismbcalpha |  | + |  |
iswalpha |  | + | + | +

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