Checking Duplicates

[Anon]

Hi
I am working on a referal system that requires a user to input a min. of 4 emails and a max. of 10. What I need is some way to check whether or not they have entered duplicate entries (ie: 10 emails that are all the same addresses), independant of the fact of whether or not they entered only 4 or all 10. Only thing I can think of is putting it into an array and then.... ?

Help is MUCH appreciated!

[[deleted]]

and then use array_unique and see if the new array is the same length as the original array.

[spacemax]

then do run a sort algorithem like Quicksort (http://www.phpbuilder.com/snippet/detail.php?type=snippet&id=10).

now use this algorithem:

pointer1 =0
pointer2=0
while{
is pointer2+1 in arraylength?
yes: is array@pointer1 equal array@pointer2
yes: error
no: still ok
pointer1=pointer2
pointer2=pointer2+1
no:end
}

because you sorted the array its possible to compare only all elements with the next element to see if there are dublicated elements

shure, this is not the shortest way but it works..

[[deleted]]

Or you could simply
loop through the array and compare every element with all the other elements like this:

for ($t=0;$t<count($array);$t++)
{
for ($tt=$t+1;$tt<count($array);$tt++)
{
if ($array[$tt]==$array[$t])
{

duplicate found

};
};
};

note that the inner loop starts and the current value of the outer look + one. that is because once I have compared the first entry with the rest, there's no need to later compare the rest with the first, etc.

[Anon]

That looks perfect! Now to try and figure out a way for it to discard empty entries.
As it stands right now all the emails are remail[1], remail[2], etc. the script sends them all even if they were filled in or not.. making 2 blank entries a duplicate :/
Any ideas on a fix for this --- been thinking about empty() or isset()...
Thanks!

[[deleted]]

for ($t=0;$t<count($array);$t++)
{
if ($array[$t]!="")
{
for ($tt=$t+1;$tt<count($array);$tt++)
{
if ($array[$tt]==$array[$t])
{

duplicate found

};
};
};
};

[Anon]

That is much more graceful than what I had come up with:

// discard blank entries

if (empty($remail[1])) {
unset ($remail[1]);
}
if (empty($remail[2])) {
unset ($remail[2]);
}
if (empty($remail[3])) {
unset ($remail[3]);
}
if (empty($remail[4])) {
unset ($remail[4]);
}
if (empty($remail[5])) {
unset ($remail[6]);
}
if (empty($remail[7])) {
unset ($remail[7]);
}
if (empty($remail[8])) {
unset ($remail[8]);
}
if (empty($remail[9])) {
unset ($remail[9]);
}
if (empty($remail[10])) {
unset ($remail[10]);
}

// check for duplicates

for ($t=0;$t<count($remail);$t++)
{
{
for ($tt=$t+1;$tt<count($remail);$tt++)
{
if ($remail[$tt]==$remail[$t])
{
$dupe=1;
}
}
}

Thanks Vincent! oh and BTW... they must pay you to post to these forums - I have never seen someone so active before!