Convert a variable from lower case to upper case

How to convert given string from lower case to upper case?
Program: 
#include<stdio.h>
#include<conio.h>
int main()
{
 char ch;
 printf("\n enter the variable in LOWER case:");
 scanf("%c",&ch);
 printf("\n the num in UPPER case is %c",ch-32);
 getch();
}
output:

 
Output of the program from lower case to upper case