PHP处理巨大的字符串

Question

I have to replace xmlns with ns in my incomming xml in order to fix SimpleXMLElements xpath() function. Most functions do not have a performance problem. But there allways seems to be an overhead as the string grows.

E.g. preg_replace on a 2 MB string takes 50ms to process, even if I limit the replaces to 1 and the replace is done at the very beginning.

If I substr the first few characters and just replace that part it is slightly faster. But not really that what I want.

Is there any PHP method that would perform better in my problem? And if there is no option, could a simple php extension help, that just does Replace => SimpleXMLElement in C?

Answer 1

If you know exactly where the offending "x", "m" and "l" are, you can just use something like $xml[$x_pos] = ' '; $xml[$m_pos] = ' '; $xml[$l_pos] = ' ' to transform them into spaces. Or transform them into ns___ (where _ = space).