Re: Empty String confusion; Positive and Natural

["Jeffrey R.Carter" <spam.jrcarter.not@spam.acm.org.not>]

On 2021-11-29 23:50, Kevin Chadwick wrote:
> 
> Hopefully I will have a doh moment when I get into the office in the morning and post code. I am getting a range check exception when I assign "" to a standard.String in a record by returning the record from a function. Surely, I must have caused it somehow.

It sounds as if you think type String is magic. String is a 
one-dimensional array type, no different than any other one-dimensional 
array type. It is declared in ARM A.1(37/3) 
(http://www.ada-auth.org/standards/rm12_w_tc1/html/RM-A-1.html) as

type String is array(Positive range <>) of Character
       with Pack;

If you think that

type T is array (Positive range <>) of Integer;
V : T (1 .. 5);
...
V := (1 .. 0 => <>);

should work, then you don't understand arrays in Ada.

If you understand why that won't work, then

S : String (1 .. 5);
...
S := "";

is the exact same thing and fails in the same way for the same reason.

-- 
Jeff Carter
"I did not rob a bank. If I'd robbed a bank, everything
would be great. I tried to rob a bank, is what happened,
and they got me. I misspelled the note."
Take the Money and Run
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