confusing foreach loop show values of arrays

Question

Question : How to display 15 random usernames with single quote on each username in an array?

Code :

$friendsArray = array("zac1987", "peter", "micellelimmeizheng1152013142",.....);
$randomfriends = array_rand($friendsArray, 15); //random select 15 usernames

foreach($randomfriends as $c => $friend){ //wrap each username in a single quote
    $friendsArray[$c] = "'".mysql_real_escape_string($friendsArray[$c])."'";
}

$friendsArray2 = join(', ',$friendsArray);
echo $friendsArray2;

Output :

'hh', 'gg', 'ff', 'dd', 'ss', 'aa', 'oo', 'ii', 'uu', 'yy', 'tt', 'rr', 'ee', 'ww', 'qq', micellelimmeizheng1152013142, vv, bb

The problem can be seen obviously through the output. micellelimmeizheng1152013142, vv, bb are 16th, 17th and 18th entry without single quotes, they supposedly not to be shown, how to delete them?

foreach($randomfriends as $c => $friend) -- you know array_rand only returns keys, right? the => $friend is kind of moot. — Brad Christie
– Brad Christie, Commented Jul 8, 2011 at 3:29

zerkms · Accepted Answer · 2011-07-08 03:29:19Z

6

shuffle($friendsArray);
$rand = array_slice($friendsArray, 0, 15);

And sample: http://ideone.com/hjrcY

answered Jul 8, 2011 at 3:29

zerkms

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12 Comments

zac1987 Over a year ago

output is still having problem : 'tt', 'hh', 'ii', 'vv', 'uu', 'bb', 'oo', 'dd', 'yy', 'aa', 'ee', 'gg', 'ff', 'qq', 'micellelimmeizheng1152013142', ss, rr, ww

Jason McCreary Over a year ago

@zac1987, the issue lies in the rest of your code. See my extended answer that builds upon this with due credit.

zac1987 Over a year ago

I already have $randomfriends = array_rand($friendsArray, 15); and it works great. If I have 1000 records and i need to select 15 from them, which codes should be better / faster?

zerkms Over a year ago

@zac1987: if you had 1000 records - you'd better sorted/shuffled them in database and just not fetch the ones you don't need

zerkms Over a year ago

@zac1987: is that a joke? You think that ORDER BY RAND() will cause a performance issue, but fetching everything and shuffling in php - will not? o_O

|

Jason McCreary · Accepted Answer · 2011-07-08 03:41:33Z

4

Your issue is that you are not reseting $friendsArray and merely overwriting certain keys with:

$friendsArray[$c] = "'".mysql_real_escape_string($friendsArray[$c])."'";

Here's your complete, corrected code, borrowing from zerkms:

shuffle($friendsArray);
$rand = array_slice($friendsArray, 0, 15);

foreach($rand as $friend) {
    $sql_output[] = "'".mysql_real_escape_string($friend)."'";
}

$sql_output = join(', ',$sql_output);

edited Jul 8, 2011 at 3:41

answered Jul 8, 2011 at 3:34

Jason McCreary

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3 Comments

alex Over a year ago

Who is this zmayte character you speak of? :P

zac1987 Over a year ago

@Jason McCreary. WOW! It works! Thank you very much. I think function array_rand() makes things complicated.

Jason McCreary Over a year ago

@zac1987, no problem. I agree in this case the code offered by zermks is a bit more intuitive than array_rand() as it returns the keys. But either way, your original code worked had you stored the sql output in a separate array.

Aleksey Korzun · Accepted Answer · 2011-07-08 03:36:23Z

0

If you need to delete everything after the quoted strings, you can use this:

<?php

$sample = "'hh', 'gg', 'ff', 'dd', 'ss', 'aa', 'oo', 'ii', 'uu', 'yy', 'tt', 'rr', 'ee', 'ww', 'qq', micellelimmeizheng1152013142, vv, bb";
echo substr($sample, 0, strripos($sample, "'")+1)

answered Jul 8, 2011 at 3:36

Aleksey Korzun

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