PHP replace : find and replace the same characters with different text - php

Question

How can I find and replace the same characters in a string with two different characters? I.E. The first occurrence with one character, and the second one with another character, for the entire string in one go?
This is what I'm trying to do (so users need not type html in the body): I've used preg_replace here, but I'll willing to use anything else.
$str = $str = '>>Hello, this is code>> Here is some text >>This is more code>>';
$str = preg_replace('#[>>]+#','[code]',$str);
echo $str;
//output from the above
//[code]Hello, this is code[code] Here is some text [code]This is more code[code]
//expected output
//[code]Hello, this is code[/code] Here is some text [code]This is more code[/code]
But problem here is, both >> get replaced with [code]. Is it possible to somehow replace the first >> with [code] and the second >> with a [/code] for the entire output?
Does php have something to do this in one go? How can this be done?

Answer 1

$str = '>>Hello, this is code>> Here is some text >>This is more code>>';
echo preg_replace( "#>>([^>]+)>>#", "[code]$1[/code]", $str );
The above will fail if something like the following is your input:
>>Here is code >to break >stuff>>
To deal with this, use negative lookahead:
#>>((?!>[^>]).+?)>>#
will be your pattern.
echo preg_replace( "#>>((?!>[^>]).+?)>>#", "[code]$1[/code]", $str );