From: Robert Klemme <bob.news@...>
Date: 2003-11-17T10:23:29+09:00
Subject: Re: to_i


"Artur Merke" <merke@ls1.cs.uni-dortmund.de> schrieb im Newsbeitrag
news:Pine.LNX.4.33.0311101726040.17966-100000@as0203.cs.uni-dortmund.de...
Hi,

taken from the ruby book:

str.to_i -> anInteger

Returns the result of interpreting leading characters in str as a decimal
integer. Extraneous characters past the end of a valid number are ignored.
If there is not a valid number at the start of str, 0 is returned. The
method never raises an exception.

example
"hello".to_i
�
0

Is there a way to recognize if the conversion was successful? If
"0".to_i and "any string".to_i deliver the same result, I don't see how
this could be accomplished, without separately checking the syntax of the
given string.

Why doesn't "hello".to_i deliver a nil as a return value, which can
clearly be recognized as a conversion failure?

    IMHO this is a struggle between convenience and cleanness.  I guess
Matz decided for convenience in this case, maybe because in most cases
using 0 is ok.  If you want to do correct input checking you do
/^[+-]?\d+$/ =~ foo anyway.

    Kind regards

        robert