如何使用正则表达式检查四个零的每个子字符串是否后跟至少四个零? [英] How can I check if every substring of four zeros is followed by at least four ones using regular expressions?

问题描述

如何写正则表达式，其中每当有 0000 时，后面应该有 1111，例如:

How can I write regular expression in which whenever there is 0000 there should be 1111 after this for example:

00101011000011111111001111010 -> correct
0000110                       -> incorect
11110                         -> correct

感谢您的帮助

推荐答案

如果您使用的是 Perl，则可以使用 零宽度负前瞻断言:

If you are using Perl, you can use a zero-width negative-lookahead assertion:

#!/usr/bin/perl

use strict; use warnings;

my @strings = qw(
    00101011000011111111001111010
    00001111000011
    0000110
    11110
);

my $re = qr/0000(?!1111)/;

for my $s ( @strings ) {
    my $result = $s =~ $re ? 'incorrect' : 'correct';
    print "$s -> $result\n";
}

如果有 0000 not 后跟至少四个 1 的字符串，则模式匹配.因此，匹配表示不正确的字符串.

The pattern matches if there is a string of 0000 not followed by at least four 1s. So, a match indicates an incorrect string.

输出:

C:\Temp> s
00101011000011111111001111010 -> correct
00001111000011 -> incorrect
0000110 -> incorrect
11110 -> correct

这篇关于如何使用正则表达式检查四个零的每个子字符串是否后跟至少四个零?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！