isupper Function

Test for an uppercase letter.

Include

<ctype.h>

Prototype

int isupper (int c);

Argument

c

The character to test.

Return Value

Returns a non-zero integer value if the character, c, is an uppercase alphabetic character; otherwise, returns zero.

Remarks

A character is considered to be an uppercase alphabetic character if it is in the range of ‘A’-‘Z’.

Example

#include <ctype.h>
#include <stdio.h>

int main(void)
{
  int ch;

  ch = 'B';
  if (isupper(ch))
    printf("B is uppercase\n");
  else
    printf("B is NOT uppercase\n");

  ch = 'b';
  if (isupper(ch))
    printf("b is uppercase\n");
  else
    printf("b is NOT uppercase\n");
}

Example Output

B is uppercase
b is NOT uppercase