使用preg_replace的PHP:“分隔符不得为字母数字或反斜杠"；错误 [英] PHP using preg_replace : "Delimiter must not be alphanumeric or backslash" error

问题描述

我正在尝试像这样输入一串文字:

I am trying to take a string of text like so:

$string = "This (1) is (2) my (3) example (4) text";

在每个括号内有一个正整数的情况下，我想用整数本身替换它.

In every instance where there is a positive integer inside of parentheses, I'd like to replace that with simply the integer itself.

我现在使用的代码是:

$result = preg_replace("\((\d+)\)", "$0", $string);

但是我不断得到一个

分隔符不能为字母数字或反斜杠.

Delimiter must not be alphanumeric or backslash.

警告

有什么想法吗?我知道这里还有其他问题可以回答该问题，但是我对正则表达式的了解不足以将其切换到本示例.

Any thoughts? I know there are other questions on here that sort of answer the question, but my knowledge of regex is not enough to switch it over to this example.

推荐答案

您快到了.您正在使用:

You are almost there. You are using:

$result = preg_replace("((\d+))", "$0", $string);

• 您指定为第一个的正则表达式 preg_*函数族的参数 应该成对分隔 定界符.由于您没有使用 任何定界符，您都会收到该错误.
• (和)是正则表达式中的元字符， 表示它们具有特殊的含义. 由于您要匹配文字打开 圆括号和近圆括号， 您需要使用\对其进行转义. \之后的所有内容都将被处理 从字面上看.
• 您可以捕获整数 正确使用\d+.但是被俘 整数将在$1中而不是$0中. $0 将拥有整个比赛，即 括号内的整数.
• The regex you specify as the 1st argument to preg_* family of function should be delimited in pair of delimiters. Since you are not using any delimiters you get that error.
• ( and ) are meta char in a regex, meaning they have special meaning. Since you want to match literal open parenthesis and close parenthesis, you need to escape them using a \. Anything following \ is treated literally.
• You can capturing the integer correctly using \d+. But the captured integer will be in $1 and not $0. $0 will have the entire match, that is integer within parenthesis.

如果您进行了上述所有更改，您将得到:

If you do all the above changes you'll get:

$result = preg_replace("#\((\d+)\)#", "$1", $string);

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