isupper() function in ctype.h Library in C programming

#include<stdio.h>
#include<conio.h>
#include<ctype.h> // library for islower function must require it
void main()
{
       char c;
       printf("Enter character : ");
       scanf("%c",&c);
     
       if(isupper(c)==0)
           printf("Enter character is Not a upper case character");
       else
          printf("Enter character is upper case character");
getch();

}