public string SendKeyPress(char key)
{
switch (key)
{
case var c when Character.IsDigitOrDot(c):
UpdatedDisplay = Operands.UpdateOperands(c);
break;
case var c when Character.IsSymbol(c):
UpdatedDisplay = DoOperation(c);
break;
case var c when Character.IsToggle(c):
UpdatedDisplay = Operands.ChangeSign();
break;
case var c when Character.IsSetZero(c):
UpdatedDisplay = SetZero();
break;
default: //ignoring other characters and return previous displayed string
break;
}
if (Character.IsInfinity(UpdatedDisplay))
{
Operands.Reset();
UpdatedDisplay = "0";
return(ERROR);
}
return(UpdatedDisplay);
}