**`iswupper()`** is a built-in function defined in the `<wctype>` header in C.

The function checks whether or not the given wide character is an uppercase letter. This check is specific to the current locale being used.

# Syntax

The function prototype:

```C
int iswupper(std::wint_t ch);
```

`iswupper()` returns *non-zero* if the input wide character is in uppercase. Otherwise, the function returns *zero*.

## Wide characters

A **wide character** has a size greater than the traditional 8-bit character.

A wide string literal is prefixed by `L`.

/* iswlower example */
#include <stdio.h>
#include <stddef.h>
#include <wctype.h>
int main ()
{
  int i=0;

  //wide string literal -- all UPPERCASE
  wchar_t str[] = L"HeLlO WoRlD!";

  //wide char for input
  wchar_t c;

  //loop to iterate over each char in str
  while (str[i])
  {
    c = str[i];
    if (iswupper(c))
      printf("%c --> UPPERCASE\n", c);
    
    else
      printf("%c --> not uppercase\n", c);

    i++;
  }
  return 0;
}

What is iswupper() in C?

iswupper() checks if a wide character is uppercase in the current locale, returning non-zero if true.

What is iswupper() in C?

Syntax

Wide characters

Code