[mercury-users] Strange behavior of string__to_int in Mercury

[Gregory D. Weber]

If S = "+" or "-", then 

string__to_int(S, I)

succeeds with I = 0.

Shouldn't it succeed only if S has at least one digit?
(It does fail if S = "".)

Whether this is a bug or an annoying feature, it is easy to work around
with

S \= "+",
S \= "-",
string__to_int(S, I)

>From the library documentation:

:- func string__det_to_int(string) = int.
%	Converts a signed base 10 string to an int;
%	throws an exception if the string argument
%	does not match the regexp [+-]?[0-9]+

:- pred string__to_int(string, int).
:- mode string__to_int(in, out) is semidet.
% 	Convert a string to an int.  The string must contain only digits,
% 	optionally preceded by a plus or minus sign.  If the string does
% 	not match this syntax, string__to_int fails.

If I read this correctly, then it is indeed a bug.

-- 
Gregory D. Weber

Associate Professor of Computer Science, Indiana University East
2325 Chester Boulevard, Richmond, Indiana 47374-1289, U.S.A.
Telephone: (765) 973-8420         World-Wide Web http://mypage.iu.edu/~gdweber/


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