为什么Java和Perl中的正则表达式有不同的表现？ [英] Why do regular expressions in Java and Perl act differently?

问题描述

我的理解是Java的正则表达式的实现是基于Perl的。但是，在下面的示例中，如果我使用相同的字符串执行相同的正则表达式，Java和Perl会返回不同的结果。

My understanding is that Java's implementation of regular expressions is based on Perl's. However, in the following example, if I execute the same regex with the same string, Java and Perl return different results.

这是Java示例：

public class RegexTest {
    public static void main( String args[] ) {
        String sentence = "This is a test of regular expressions.";
        System.out.println( sentence.matches( "\\w" ) ? "Matches" : "Doesn't match" );
    }
}

返回：不匹配

以下是Perl示例：

my $sentence = 'This is a test of regular expressions.';
print ( $sentence =~ /\w/ ? "Matches" : "Doesn't match" ) . "\n";

返回：匹配

给我，Perl结果很有意义。它查找单个单词字符的匹配项。我不明白为什么Java不认为它是匹配的。造成这种差异的原因是什么？

To me, the Perl result makes sense. It looks for a match for a single word character. I don't understand why Java doesn't consider it a match. What's the reason for the difference?

推荐答案

Java 匹配方法是测试正则表达式是否匹配整个 String 。要测试是否可以在字符串中的任何位置找到正则表达式，请创建 Matcher 并使用其 find 方法。

The Java matches method is testing whether the regex matches the entire String. To test whether a regex can be found anywhere in a string, create a Matcher and use its find method.

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