Comparison functions for qsort() and bsearch()

[Barry Margolin]

In article <277640DD.4A70 at tct.uucp> chip at tct.uucp (Chip Salzenberg) writes:
>>In short, IT IS IMPOSSIBLE TO WRITE QSORT() ENTIRELY IN ANSI C OR IN C++
>>IN SUCH A WAY THAT IT IS COMPLETELY PORTABLE.
>This statement is false.  It is entirely possible to do so, thanks to
>ANSI's guarantee that pointer-to-char and pointer-to-void will always
>have identical representations.

I think Chip is correct about C, but not necessarily about C++.  Actually,
qsort() itself can be written portably in C++, but it's hard to write most
comparison functions portably.  The problem is that C++ has restrictions on
casting from void* into <type>*.  So, you can pass the void* parameters to
the comparison function, but it may not be able to do anything with them.

--
Barry Margolin, Thinking Machines Corp.

barmar at think.com
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