On May 6, 2:36?pm, Nathan <nathancba...@gmail.com> wrote:
On Apr 28, 1:16?am, Juha Nieminen <nos...@thanks.invalid> wrote:
? Care to show an actual example of your "simpler, cleaner and easier to
follow" version of exiting a nested loop by meddling with the loop
conditions instead of using 'return'? For example, modify the following
code to conform to your specifications:
Value_t* MyClass::findValue(const Value_t& value)
{
? ? for(size_t xInd = 0; xInd < data.size(); ++xInd)
? ? ? ? for(size_t yInd = 0; yInd < data[xInd].size(); ++yInd)
? ? ? ? ? ? for(size_t zInd = 0; zInd < data[xInd][yInd].size(); ++zInd)
? ? ? ? ? ? {
? ? ? ? ? ? ? ? if(data[xInd][yInd][zInd] == value)
? ? ? ? ? ? ? ? ? ? return &data[xInd][yInd][zInd];
? ? ? ? ? ? }
? ? return 0;
}
Hi Juha,
I think that you either copied this from a poorly-written beginner C++
book or you failed to understand what the author was attempting to
demonstrate with that kind of code and that you did not 'catch on'
that it is not (in any way) demonstrative of how one walks a series of
sequential cells in the real world.
Why do you insist on writing control structures that serve little
actual purpose? ?For instance, it should be obvious that you only
require ONE loop and a few conditionals to achieve your desired (or
assumed) goal. ?E.G...
,---
result = value
xInd = 0
yInd = 0
zInd = 0
while ( data[xInd][yInd][zInd] != value && result != 0)
{
? ? ++zInd;
? ? if (( zInd < data[xInd][yInd].size() ) != true ) { zInd = 0; +
+yInd};
? ? if (( yInd < data[xInd].size() ) != true ) { yInd = 0; ++xInd};
? ? if (( xInd < data.size() ) != true ) { result = 0 };}
return result
`---
Juha did ask for something "simpler, cleaner and easier to follow",
which your single loop is not. Perhaps because of that, your code
needlessly compares yInd and xInd to their respective limits on every
iteration, rather than something like...
while ( data[xInd][yInd][zInd] != value && result != 0)
{
if {++zInd == data[xInd][yInd].size()) {
zInd = 0;
if (++yInd == data[xInd].size()) {
yInd = 0;
if (++xInd == data.size())
result = 0;
}
}
...
More importantly, it can dereference index [0] before checking size(),
so produces undefined behaviour. Anyway, IMHO it's far less clear
(=self-evidently correct & efficient as well as maintainable) than
Juha's code.
Of course, this is a rather useless (maybe even retarded) function to
begin with, because it only tells you IF the 'value' is located
"somewhere" within that array -- it gives you absolutely no indication
of "where" in that array you might be able to access the item which
matches your search criteria.
You missed that the original function was returning a pointer to the
matching cell, allowing a change to be made at that location,
considerably more useful than the search-term-else-0-sentinel version
you coded.
Please pardon any butchering of C++ syntax in my pseudo snippet above
-- I totally lack any C++ training.
Fair enough... no worries.
?But we alt.lang.asm folk *do*
have an inkling of how to actually code our way out of a paper bag...
I do believe.
Nathan.
Your central point that a single loop can serve contributes an
interesting alternative, which I'm sure the readers here will
appreciate, if they bother to look past your smug attitude (which is
quite unwarranted given the serious errors in your implementation)....
I posted a single loop alternative last week or so. I think it is a much