C Program to Convert Lowercase to Uppercase

#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
char sk[15];
int i;
clrscr();
printf("Enter a string :");
gets(sk);
for(i=0;i<strlen(sk);i++) if(sk[i]>='a' && sk[i]<= 'z')
sk[i]=sk[i]-32;
printf("The converted upper case string is %s", sk);
getch();
}