To toggle character

//program made by Puneet Sharma
#include
#include
//To toggle character
char toggle(char);
void main()
{
char arr[16];
int c,i; char a;
clrscr();
scanf("%s" , arr);
for(i=0;arr[i]!='\0';i++)
{
a= toggle(arr[i]) ;
printf("%c",a);
}
}
char toggle(char c)
{
if(c>=65 && c<=122)
{
if(c>=97)
return(c-32);
else
return(c+32);
}
}