php regex:电话号码7到12位数字可能包含连字符或空格 [英] php regex: phone number 7-12 digits may contain hypen or space
问题描述
我尝试了以下链接中包含7-12位数字的电话号码的解决方案，其中可能包含空格或连字符.第一个和最后一个字符必须是数字.
I tried the solution for phone numbers with 7-12 digits that may contain spaces or hypens in the following link. The first and last character has to be a number.
但是，我对正则表达式不太了解.
However, i'm not understanding the regex well.
$phone_pattern="/^\d(?:[-\s]?\d){6,11}$/";
:"在这里是什么意思?
what does the ":" mean here?
此正则表达式如何排除6到11个字符之间的连字符和空格?
How is this regex able to exclude the hypens and spaces from the 6 to 11 characters?
非常感谢帮助
推荐答案
您是否尝试过像regexpal这样的测试引擎(还有其他可用的引擎)，我经常使用它来针对表达式测试各种字符串，以确保它们的行为符合预期
Have you tried a testing engine like regexpal (there are others available also) I frequently use this to test various strings against expressions to make sure they are behaving as expected.
我的理解是，在这种情况下，:不是单独行动，而是与?
My understanding is that in this case the : is not acting alone it is acting in conjunction with the ?
在这种情况下，?并不意味着它是修饰语之前的零或一倍，这给该组赋予了新的含义，并与修饰符:一起关闭capture表示您希望这是一个非捕获的组表达式.
The ? in this circumstance does not mean Preceding zero or one times it is a modifier meaning give this group a new meaning which in conjunction with the modifier : turn off capture means you want this to be a non capturing group expression.
其效果是，将表达式的一部分放置在()内时，默认情况下会引起捕获，但?:会将其关闭.
The effect that this has is that when placing part of an expression inside () it by default causes capture but ?: switches this off.
因此(?:[-\ s]?\ d)成为非捕获组表达式.
Thus (?:[-\s]?\d) becomes a non capturing group expression.
注释捕获组与反向引用一起使用，大多数正则表达式引擎最多支持9个反向引用.
Note captured groups are used with back references and most regex engines support up to 9 back references.
因此，删除捕获可加快匹配过程，并允许您选择不回溯该组，从而将9个引用中的一个保存为您确实要回溯的组.
So removing capture speeds up the matching process and allows you to elect not to refer back to that group saving one of your 9 references for a group that you really do want to refer back to.
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