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C ctype islower() Function

❮ C ctype Library


Example

Check if a character is a lowercase letter:

char c = 'b';
if (islower(c)) {
  printf("%c is a lowercase letter", c);
} else {
  printf("%c is not a lowercase letter", c);
}
Try it Yourself »

Definition and Usage

The islower() function returns a non-zero value (equivalent to boolean true) if a character is a lowercase letter.

The islower() function is defined in the <ctype.h> header file.


Syntax

int islower(int c);

Parameter Values

Parameter Description
c Required. The ASCII value of a character or an actual character

Technical Details

Returns: An int value which is non-zero (equivalent to boolean true) if the character is a lowercase letter.

Otherwise it returns 0 (equivalent to boolean false).

❮ C ctype Library