UPPERCASE TO LOWERCASE AND VICE CERSA

#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
char a[20],b[20];
clrscr();
printf("\n Enter a word \n");
scanf("%s",a);
printf("\n Enter another Word \n");
scanf("%s",b);
strupr(a);
strlwr(b);
printf("\n After Change= %s",a);
printf("\n After CHange= %s",b);
getch();
}