php string manipulation nonrandom sort

I am trying to sort a 4 characte开发者_Go百科r string thats being feed in from a user into a different order. an example might be they type "abcd" which I then take and turn it into "bcad".

Here is an example of my attempt which is not working :P

<?php

$mixedDate = $_REQUEST['userDate'];

$formatted_date = firstSubString($mixedDate,2).secondSubString($mixedDate,3).thirdSubString($mixedDate,1).fourthSubString($mixedDate,4);

//... maybe some other stuff here then echo formatted_date
?>

any help would be appreciated.

Copied from comment:

You could pretty simply do this by doing something like:

$formatted_date = $mixedDate[1].$mixedDate[2].$mixedDate[0].$mixedDate[3];

That way, you don't have to bother with calling a substring method many times, since you're just moving individual characters around.

<?php
$mixedDate = $_REQUEST['userDate'];

$formatted_date = $mixedDate{1}.$mixedDate{2}.$mixedDate{0}.$mixedDate{3};

echo $formatted_date;
?>

The curly syntax allows you to get just that one character from your string.

It should be noted that this works correctly on your sample string, abcd and turns it into bcad if $_REQUEST['userDate'] is abcd.

Look into split() in php. It takes a string and a delimiter then splits the string into an array. Either force the user to use a certain format or use a regex on the input string to put the date into a known format, like dd/mm/yyyy or dd-mm-yyyy, then use the hyphen or / as the delimiter.

Once the string is split into an array, you can rearrange it any way you like.

That is very simple.

If

$mixedDate = 21-12-2010

then, try this

echo substr($mixedDate, 3, 2).'-'.substr($mixedDate, 0, 2).'-'.substr($mixedDate, 6);

this will result in

12-21-2010

This is assuming the format is fixed.

Use str_split() to break the string into single characters:

$char_array = str_split($input_string);

If you know exactly what order you want, and you only have four characters, then from here you can actually just do it the way you wanted from your question, and concatenate the array elements back into a single string, like so:

$output_string = $char_array[2].$char_array[3].$char_array[1].$char_array[4];

If your needs are more complex, you can sort and implode the string:

Use sort() to put the characters into order:

sort($char_array);

Or one of the other related sorting functions that PHP provides if you need a different sort order. If you need an sort order which is specific to your requirements, you can use usort(), which allows you to write a function which defines how the sorting works.

Then re-join the characters into a single string using implode():

$output_string = implode($char_array);

Hope that helps.