If variable equals variable change a variable

Question

I was wondering how I can make it to where 3 variables never have the same number using rand()?

<?php
$myAd[1] = '<a href="http://www.pegor.com">Free PHP Tutorials</a>';
$myAd[2] = '<a href="http://www.lifestinks.info">Fast Facebook Proxy</a>';
$myAd[3] = '<a href="http://www.mozilla.org">Fastest and Secure Web Browser</a>';

$adId = rand(1,count($myAd));
$adId2 = rand(1,count($myAd));
$adId3 = rand(1,count($myAd));
if ($adId === $adId2) { $adId = ($adId2 - 1) }
if ($adId === $adId3) { $adId = ($adId3 - 1) }
if ($adId2 === $adId3) { $adId2 = ($adId3 - 1) }

echo $myAd[$adId];
echo '<br>';
echo $myAd[$adId2];
echo '<br>';
echo $myAd[$adId3];
?>

In a nutshell what I would like to accomplish is my site displaying 3 products on the left column. Every time a user refreshes they change. The issue I keep running into is 2 of the variables that the random number generates are the same. How can I make it to where they always land on different numbers so 3 different products are displayed at a time instead of 2 the same and 1 different? Note: I will be adding more items to the array, that is just a test script until I figure it out.

Hmm I honestly do not understand it. My code works if I remove all the if statements. The only issue is sometimes 2 of the displayed items will be the same. Is there not a possibility of saying if this variable equals this variable subtract or add this? — VampireNews
– VampireNews, Commented Apr 26, 2013 at 8:25
The main problem with your code is that sometimes (actually, something like a 2 in 3 chance) you will be deducting 1 from 1, which will mean 0, and there is nothing in $myAd[0]. So it will error. — Paul Gregory
– Paul Gregory, Commented Apr 26, 2013 at 8:40
I added one at 0 because I caught my error but I did accept CORRUPTs answer since it worked for what I needed. Especially since they used the foreach function. I planned on placing each product in a seperate div but with foreach I can easily let it create the divs for me for each product. Thanks for the help anyway though :) — VampireNews
– VampireNews, Commented Apr 26, 2013 at 8:43
Indeed, the secondary problem was that "If variable equals variable change a variable" is an inefficient way to pick three different values. You now have chosen a solution that elegantly solves your problem but doesn't actually answer your title question. Also, you did not need to add "Resolved" to your title. — Paul Gregory
– Paul Gregory, Commented Apr 26, 2013 at 8:47

BlitZ · Accepted Answer · 2013-04-26 08:31:41Z

1

Try shuffle() and array_slice():

$myAd = array();
$myAd[1] = '<a href="http://www.pegor.com">Free PHP Tutorials</a>';
$myAd[2] = '<a href="http://www.lifestinks.info">Fast Facebook Proxy</a>';
$myAd[3] = '<a href="http://www.mozilla.org">Fastest and Secure Web Browser</a>';
// more of...

shuffle($myAd);

$myAd = array_slice($myAd, 0, 3);

foreach($myAd as $value){
    echo $value, '<br/>', PHP_EOL;
}
?>

edited Apr 26, 2013 at 8:31

answered Apr 26, 2013 at 8:24

BlitZ

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2 Comments

VampireNews Over a year ago

But if I have 50 items in the array won't it echo all 50 items?

BlitZ Over a year ago

@VampireNews Then, array_slice() helps.

sectus · Accepted Answer · 2013-04-26 08:27:25Z

1

$adId = rand(1, count($myAd));
do
    { $adId2 = rand(1, count($myAd)); }
while ($adId2 == $adId);

do
    { $adId3 = rand(1, count($myAd)); }
while ($adId3 == $adId || $adId3 == $adId);

But better to use shuffle() and array_slice().

answered Apr 26, 2013 at 8:27

sectus

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Comments

user1088172 · Accepted Answer · 2013-04-26 08:28:14Z

0

Example how to compare two but you can improve of basically you need most

$rnd1 = rand(0,9);
do {
  $rnd2 = rand(0,9);
} while ($rnd1 == $rnd2);

Firstly you need to put your random variable to one variable and then do while where the random 1 equals to random 2 you can do more complex from what you need.

GBU

answered Apr 26, 2013 at 8:28

user1088172

2 Comments

Paul Gregory Over a year ago

Of course, when the numbers are substituted for the range of adverts, a sanity check is needed to ensure there actually are enough adverts otherwise there would be an infinite loop.

user1088172 Over a year ago

Thanks @PaulGregory for the explanation though it was a simple explanation :)

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