islower Function

Test for a lowercase alphabetic character.

Include

<ctype.h>

Prototype

int islower (int c);

Argument

c

The character to test.

Return Value

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

Remarks

A character is considered to be a lowercase 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 (islower(ch))
    printf("B is lowercase\n");
  else
    printf("B is NOT lowercase\n");

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

Example Output

B is NOT lowercase
b is lowercase