C PROGRAM TO CHANGE THE CASE OF THE CHARACTER

#include<stdio.h>
void main()
{
char c;
alp:
clrscr();
printf("enter a character\n");
scanf("%c",&c);
if((c>=65)&&(c<=90))
      {
      printf("%c",(c=c+32));
      }
else if((c>=97)&&(c<=122))
     {
     printf("%c",(c=c-32));
     }
if(((c<65)||(c>122))||((c>90)&&(c<97)))
{
goto alp;
}
getch();
}