C# determines if a string is only made up of numbers and letters (Regex.IsMatch)

Little scum · Posted on 11/2/2017 9:38:53 PM

Purpose: To determine whether a string is only composed of numbers and letters, to prevent "garbled characters", and to judge the length of the string;
Main function function: System.Text.RegularExpressions.Regex.IsMatch(strMessage, pattern)
strMessage:要判断的字符串；
pattern:判断的条件；
Regular expression uses: 1. Test patterns within strings. 2. Replace text. 3. Extract substrings from strings based on pattern matching.
Regular expression syntax: https://msdn.microsoft.com/zh-cn/library/ae5bf541 (VS.80) .aspx

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Here is an analysis of some simple syntax I currently use:
string pattern = @"^[a-zA-Z0-9]\d{2}[a-zA-Z0-9](-\d{3}){2}[A-Za-z0-9]$";
Understand: 1. ^[a-zA-Z0-9]: indicates that it begins with a case or a number;
2. /d{2}: Indicates two numbers
3. {a-zA-Z0-9}: Indicates two numbers followed by a case or number
4. (-\d{3}){2}: Indicates a series of repeated -plus three number formats, such as: -333-444, -123-456
5. [A-Za-z0-9]$: Indicates that it ends in upper and lower case or number;
Correct form: 1111-111-1111;

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Understand:
Each character in the entire string must be case-case or numeric;

[Source] C# determines if a string is only made up of numbers and letters (Regex.IsMatch)

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