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

Program:

The source code to check a given character is a whitespace 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 an uppercase character or not
// without using library function

#include <stdio.h>

int isUppercase(char ch)
{
    if (ch >= 'A' && ch <= 'Z')
        return 1;
    return 0;
}

int main()
{
    char ch;

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

    if (isUppercase(ch))
        printf("Given character is an uppercase character\n");
    else
        printf("Given character is not an uppercase character\n");

    return 0;
}

Output:

RUN 1:
Enter character: G
Given character is an uppercase character

RUN 2:
Enter character: q
Given character is not an uppercase character

Explanation:

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

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