isupper

Character classification macro.

Defined in header <ctype.h>

Syntax

#include <ctype.h>
int isupper(int c);

Portability

Remarks

isupper is a macro that classifies ASCII-coded integer values by table lookup. It is a predicate returning nonzero for true and 0 for false. It is defined only when isascii(c) is true or c is EOF.

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

Return value

isupper returns nonzero if c is an uppercase letter (A to Z).

Example

#include <ctype.h>
#include <stdio.h>
int main(void)
{
   char c = 'C';
   if (isupper(c))
      printfC'lc is upper case\n",c);
else
   printf("%c isn't upper case\n",c);
return 0;

Differences from modern implementations

Nothing recorded yet.

Modern references

• cppreference (search)
• POSIX (search)
• Microsoft C runtime (search)

These are search links, not yet checked by hand.

Stable link: /3.1/ctype.h/isupper/ · short form /3.1/isupper/