# <wctype.h>

**[<wctype.h>](https://en.cppreference.com/w/c/header/wctype)** provides wide-character classification (`iswalpha`, `iswdigit`, `iswspace`) and case conversion (`towupper`, `towlower`). These functions work on full Unicode via `wchar_t`, unlike `<ctype.h>` which handles only ASCII.

Results depend on locale; call `setlocale(LC_ALL, "")` for correct Unicode support.

## Example

This example classifies and case-converts wide characters in a string.

```c
// compile: gcc -o wctypeexample wctypeexample.c
// run: ./wctypeexample
// description: classify and case-convert wide characters

#include <wctype.h>
#include <wchar.h>
#include <locale.h>

int main() {
    setlocale(LC_ALL, "");
    
    const wchar_t* s = L"héLLo 42!";
    for (const wchar_t* p = s; *p; p++) {
        wprintf(L"'%lc'  alpha=%d  digit=%d  upper=%d  upper→%lc\n",
                *p,
                iswalpha(*p) != 0,
                iswdigit(*p) != 0,
                iswupper(*p) != 0,
                towupper(*p));
    }
    
    return 0;
}
```

## Common functions

**Character classification** (return non-zero if true):
- `iswalpha(c)`: letter
- `iswdigit(c)`: decimal digit
- `iswalnum(c)`: alphanumeric
- `iswspace(c)`: whitespace
- `iswpunct(c)`: punctuation
- `iswprint(c)`: printable
- `iswcntrl(c)`: control character
- `iswupper(c)`: uppercase
- `iswlower(c)`: lowercase
- `iswxdigit(c)`: hex digit

**Case conversion**:
- `towupper(c)`: convert to uppercase
- `towlower(c)`: convert to lowercase
- `towctrans(c, trans)`: apply locale-specific transform

**Locale-specific classification**:
- `wctype(name)`: get character class by name
- `iswctype(c, type)`: test membership in class