islower() in C

 The "islower()" function in C is a part of the standard C library.

 It checks whether a given character is a lowercase alphabetic letter.

Syntax of  islower():

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

Parameters:

 c: It's an integer representing the character to be checked.

---

Return Value:

 The function returns a value greater than zero if the character is a lowercase letter.

Returns 0 otherwise.

---

Algorithm:

The function takes an integer representing a character as input.

It checks if the character is within the range of lowercase alphabetic characters(ASCII values 97 to 122).

If the character is a lowercase letter, the function returns a value that is not zero.

---

Example:

Using islower() to Check Lowercase Character:

// program for Using islower() to check lowercase character
#include<stdio.h>	
#include<ctype.h>		

int main() {
    char ch = 'a';
    
    if (islower(ch)) {
        printf("%c is a lowercase character.\n", ch);
    } else {
        printf("%c is not a lowercase character.\n", ch);
    }

    return 0;
}			

Output:

a is a lowercase character.

Counting Lowercase Characters in a String:

// program for counting lowercase characters in a string 
#include<stdio.h>	
#include<ctype.h>		

int main() {
    char str[] = "Hello World";
    int count = 0;
    for (int i = 0; str[i] != '\0'; i++) {
        if (islower(str[i])) {
            count++;
        }
    }
    printf("Number of lowercase characters in the string: %d\n", count);
    return 0;
}			

Output:

Number of lowercase characters in the string: 8