不能用echo输出正则表达式数组.注意:未定义偏移量:0.如何修复它 - Can not output regex array with echo. Notice: Undefined offset: 0. How to fix it?

Can not output regex array with echo. Notice: Undefined offset: 0. How to fix it?

$from= "You can win $200,000 tonight.";
$output = preg_match("/'$['d',]+/", $from, $matches);
echo $matches[0];

这是不工作。它给了我这个错误:

注意:未定义偏移量:0

我想输出"$200,000"。

感谢您的帮助。

try

$output = preg_match("/''$['d',]+/", $from, $matches);

你必须用双引号'

转义两次$符号http://ideone.com/digsP

你用正则表达式的双引号把自己打到了膝盖上。试试这个:

$from= "You can win $200,000 tonight.";
if(preg_match("/'$['d',]+/", $from, $matches)) {
  echo $matches[0];
}

你看，没有匹配。您必须转义两次，一次用于字符串，一次用于正则表达式引擎:

$from= "You can win $200,000 tonight.";
if(preg_match("/'''$['d',]+/", $from, $matches)) {
  echo $matches[0];
}

HTH,CK

转义$两次

$output = preg_match("/''$['d',]+/", $from, $matches);