除非前面有转义字符，否则使用 preg_replace 替换字符 [英] use preg_replace to replace character unless an escape character precedes

问题描述

我正在尝试执行以下操作，希望周围有 reg_ex 专家可以提供一些帮助.我需要替换代码中的字符 [ 并将其设为 {.但在某些情况下， [ 需要保持为 [ 而不会改变.所以我认为我需要使用

i'm trying to do the following hope there's a reg_ex expert around to shed some light. I need to replace the character [ in my code and make it a {. But there is cases where the [ needs to remain a [ and not change. So the way i figured it is i need to use the

preg_replace("[", "{", $string);

preg_replace("[", "{", $string);

具有合适的正则表达式的函数将导致 [ 前面没有要使用的转义字符的字符可以说 .那么我怎样才能替换这个["而不是这个["?

function with a suitable regular expression that will result the [ characters that are not preceded by the escape character to be used lets say . So how can i get to replace this "[" and not this "["?

非常感谢

推荐答案

你可以做到这一点，它是一个约定调用否定后视断言

You can do this, and it's with a convention call negative lookbehind assertions

echo preg_replace( "/(?<!\\\\)\\[/", '{', "\[ [ [ \[ [" );

基本上，仅当前面没有 \"时才将 [ 替换为 {

Basically, "replace [ with { only when not preceded by \"

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