.NET & C# VALIDATOR

Online C# & ASP.NET Regex Validator

.NET reguläre Ausdrücke erstellen und prüfen. System.Text.RegularExpressions Muster und C#-Code in Echtzeit generieren.

C# Regex Engine Simulator

RegexOptions.IgnoreCase | RegexOptions.Compiled

C# Verbatim String Pattern

@""

Test String

Regex.IsMatch(input) == true

Modern .NET 8/9 C# Code

// C# 11+ Source Generator
[GeneratedRegex(@"^[A-Z]2\d4[A-Z0-9]?$", RegexOptions.IgnoreCase)]
private static partial Regex MyValidator();

bool isValid = MyValidator().IsMatch(input);

C# & ASP.NET Regular Expression Architecture

Finding a dedicated c# regex validator and online regex validator c# ensures full compatibility with the .NET runtime engine. Whether you are validating models in ASP.NET Core Web APIs or writing high-performance parsers, .NET offers world-class regex performance when configured properly.

ASP.NET Model Validation

In ASP.NET Core MVC and Web APIs, model properties can be verified via the asp regex validator pattern using [RegularExpression]:

public class UserModel {
  [Required]
  [RegularExpression(@"^[a-zA-Z0-9_-]{3,16}$", 
    ErrorMessage = "Username must be 3-16 chars.")]
  public string Username { get; set; }
}

Zero-Allocation [GeneratedRegex]

Traditional new Regex(...) compiles patterns dynamically at runtime, consuming memory and cycles. With .NET 7+, always prefer compile-time source generation:

// Emits optimized C# code at build time
[GeneratedRegex(@"^\d{5}(-\d{4})?$")]
public static partial Regex ZipCodeRegex();

C# & ASP.NET Regex Validation FAQ

How do I use verbatim string literals for regex in C#?

Prefix your string with the @ symbol: @"^\d{3}-\d{2}-\d{4}$". In verbatim strings, backslashes are treated literally, eliminating the need to escape backslashes (no need for \\d).

What is [GeneratedRegex] in .NET 7, 8, and 9?

[GeneratedRegex] is a C# source generator attribute introduced in .NET 7. It inspects your regex pattern at compile time and emits strongly-typed, optimized C# code that runs with zero parsing overhead and zero allocations.

How do I use ASP.NET Core model validation with regex?

Apply the [RegularExpression(@"pattern", ErrorMessage = "Validation failed")] attribute to model or DTO properties in ASP.NET Core controllers and Razor pages.