Shulou(Shulou.com)06/02 Report--

This article introduces the knowledge of "regular expression rules in Javascript and C#". Many people will encounter this dilemma in the operation of actual cases, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

First, the concept of regular expression:

In computer science, a single string used to describe or match a series of strings that conform to a syntactic rule. In many text editors or other tools, regular expressions are often used to retrieve and / or replace text content that matches a pattern. Many programming languages support string manipulation using regular expressions.

Second, the use of regular expressions:

In ASP.NET, regular expressions are mainly used to validate the input. There are generally two types of verification: client-side JS verification and server-side verification.

1. JS validates the input

The copy code is as follows:

Function check () {

Var match = / ^\ dbuyer /

Var val = $("# txt") .val ()

If (match.test (val)) {

Alert ("Test passed")

}

Else {

Alert ("Test failed")

}

}

2. C # for verification format

The copy code is as follows:

Protected void Button1_Click (object sender, EventArgs e)

{

String pattern = @ "\ d"

If (System.Text.RegularExpressions.Regex.IsMatch (this.TextBox1.Text, pattern))

{

ClientScript.RegisterClientScriptBlock (GetType (), "", "alert ('successful verification!')", true)

}

Else

{

ClientScript.RegisterClientScriptBlock (GetType (), "", "alert ('verification failed!')", true)

}

}

III. Regular expression rules

\: Mark the next character as a special character, or a literal character, or a backward reference, or an octal escape character; for example,'n 'matches the character "n".' \ n' matches a newline character. The sequence'\ 'matches "\" and "(" matches "(".

^: matches the starting position of the input string.

$: matches the end of the input string.

*: matches the previous subexpression zero or more times. For example, zo* can match "z" and "zoo". * is equivalent to {0,}.

+: matches the previous subexpression one or more times. For example, 'zo+' can match "zo" and "zoo", but not "z". + is equivalent to {1,}.

Matches the previous subexpression zero or once. For example, "do (es)?" Can match "do" in "do" or "does". ? It is equivalent to {0jue 1}.

{n}: n is a non-negative integer. Match the determined n times. For example,'o {2} 'does not match the' o'in 'Bob', but does match the two o in 'food'.

{n,}: n is a non-negative integer. Match at least n times. For example,'o {2,} 'does not match' o'in 'Bob', but does match all o in 'foooood'. O {1,}'is equivalent to 'oasis'. O {0,}'is equivalent to 'oval'.

{n ~ (m)}: M and n are non-negative integers, where n

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.