php如何替换特殊字符前后的字符

Question

I have a php string like:

$string = '1234532323%A73823823221A%221312373712';

the string has numbers and 2 special tags (%A and A%) to indicate the begin and the end of the special part, respectively.

My goal is to replace all "1" with "2", but not in the part of the string between %A and A%.

If I use strtr(string,"1","2") all 1 occurrences will be replaced. Does anyone know how my goal can be achieved?

Special characters may appear several times inside the string.

Answer 1

You can do that by breaking them apart and replacing the strings. do look into preg_* to better solve all cases.

$a = "1234532323%A73823823221A%221312373712";
//explode to an array of 3 objects
$b = explode('%',$a);
//replace the numbers in the first and last object
$b[0] = strtr($b[0],"1","2");
$b[2] = strtr($b[2],"1","2") ;
//concatenate them again to get $a
$a = $b[0].$b[1].$b[2];

echo($a);