C islower() function

C islower(int ch)

The islower() function is used to check whether a character is lowercase alphabet (a-z) or not. The function is defined in the ctype.h header file.

Note: Letter case is the distinction between the letters that are in larger uppercase or capitals (or more formally majuscule) and smaller lowercase (or more formally minuscule) in the written representation of certain languages.

Syntax:

int islower( int arg );

islower() Parameters:

Return value from islower()

• The islower() function returns non-zero if ch is a lowercase letter; otherwise, returns 0.

Example: C islower() function

#include <stdio.h>
#include <ctype.h>
int main()
{
    char ch;
    ch = 'y';
    printf("\nIf %c is lower character or not? %d", ch, islower(ch));
    ch = 'Y';
    printf("\nIf %c is lower character or not? %d", ch, islower(ch));
    ch = 'A';
    printf("\nIf %c is lower character or not? %d", ch, islower(ch));
}

Output:

If y is lower character or not? 2
If Y is lower character or not? 0
If A is lower character or not? 0

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