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C program to check a given character is a lowercase character or not without using the library function

Here, we are going to learn how to check a given character is a lowercase character or not without using the library function in C programming language?
Submitted by Nidhi, on July 16, 2021

Problem statement

Given a character, we have to check whether the given character is a lowercase character or not without using the library function.

Program

The source code to check a given character is a lowercase character or not without using the library function is given below. The given program is compiled and executed using GCC compile on UBUNTU 18.04 OS successfully.

// C program to check a given character is a lowercase character or not
// without using library function

#include <stdio.h>

int isLowercase(char ch)
{
    if (ch >= 'a' && ch <= 'z')
        return 1;

    return 0;
}

int main()
{
    char ch;

    printf("Enter character: ");
    scanf("%c", &ch);

    if (isLowercase(ch))
        printf("Given character is a lowercase character\n");
    else
        printf("Given character is not a lowercase character\n");

    return 0;
}

Output

RUN 1:
Enter character: q
Given character is a lowercase character

RUN 2:
Enter character: G
Given character is not a lowercase character

Explanation

In the above program, we created two functions isLowercase() and main(). The isLowercase() function is used to check the given character is a lowercase character or not.

In the main() function, we read a character from the user and check given character is a lowercase character or not by calling isLowercase() function and print the appropriate message on the console screen.

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