Re: += in ada

[christoph.grein@eurocopter.com]

> > with Text_IO; use Text_IO;
> > with Integer_Text_IO; use Integer_Text_IO;
> > procedure Issue is
> >    X,Y,Z: Integer := 0;
> > begin
> >    Get(X); Get(Y);
> >    if X * Y > Integer'Last

X and Y may be kept in registers and also the result, and the registers may well 
be able to hold values above Integer'Last.

The RM specifies that either an exception be raised or the mathematically 
correct result (here Boolean True) be returned. [Only when the result is 
assigned to an Integer must the exception be raised. There is no assignment in 
the if-statement's expression.]

> >    then
> >      Put_Line("Overflow!");
> >    else
> >      Z := X * Y;
> >      Put_Line("Okay");
> >    end if;
> > exception when Constraint_Error =>
> >    Put("Exception Raised. Z = ");
> >    Put(Z);
> >    New_Line;
> > end Issue;
> What,there are exception in X * Y > Integer'Last 
> if there are overflow on X*Y?
> And if so,how Put_Line("Overflow!"); could work?
> 
> (yes ,i'm is a newbie to ada)