From: David Abrahams (dave_at_[hidden])
Date: 2004-01-05 06:31:53
"Michael D. Borghardt" <michael_at_[hidden]> writes:
> How about this to handle unsigned to signed conversion?
>
> template <>
> struct greater_than_type_max<false, false>
> {
> template <class X, class Y>
> static inline bool check(X x, Y y_max)
> { return (sizeof(Y) > sizeof(X) ? static_cast<Y>(x) > y_max : x >
> static_cast<X>(y_max));}
> // { return static_cast<X>(static_cast<Y>(x)) != x; } // this is the
> original line
> };
I can't quite read your code; more line breaks would help ;-)
Using sizeof is a pretty good heuristic, but it's not strictly
portable. The number of chars in a numeric type says nothing about
its range according to the standard.
> I created the matrix below with test cases and I have tested the following
> so far
>
> The orginal line fails tests 6-9,17,19,20,26,33,34,36,37,39,40 where each
> uses the sources MAX value
I'm sure it would be a really useful table, but the formatting didn't
quite come out. Would you mind doing a re-post?
> columns represent the source and the rows represent the target
>
> char unsigned char signed char short unsigned short signed short int
> unsigned int signed int long unsigned long signed long float double
> char 33 PASS 15 17 21 27 34 41
> unsigned char 12 13 18 22 28 35 42
> signed char 6 16 19 23 29 36 43 1,2
> short PASS PASS 20 PASS 30 37 44
> unsigned short PASS PASS 10 24 31 38 45 25
> signed short PASS PASS PASS 9 32 39 46
> int PASS PASS PASS PASS PASS 40 PASS 5
> unsigned int PASS PASS PASS PASS PASS 11 14
> signed int PASS PASS PASS PASS PASS PASS 7
> long PASS PASS PASS PASS PASS PASS PASS PASS
> unsigned long PASS PASS PASS PASS PASS PASS PASS PASS 3,4
> signed long PASS PASS PASS PASS PASS PASS PASS PASS PASS 8
> float PASS PASS PASS PASS PASS PASS PASS PASS PASS 26
> double PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS
>
>
>
>
>
>
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-- Dave Abrahams Boost Consulting www.boost-consulting.com