Have you faced tasks of verifying input data correctness?

Yes, input validation is an important task to ensure the stability and security of applications in C#.

Main approaches:

• Using validation attributes from the namespace System.ComponentModel.DataAnnotations, such as [Required], [Range], [StringLength].
• Validation in ASP.NET controllers using ModelState.IsValid.
• Creating custom validators or using libraries like FluentValidation.
• Manually checking data with conditional operators and throwing exceptions on errors.

Example with attributes:

public class User
{
    [Required]
    public string Name { get; set; }

    [Range(18, 99)]
    public int Age { get; set; }
}

// In the controller
if (!ModelState.IsValid)
{
    return BadRequest(ModelState);
}

This approach helps to centrally define rules and automatically validate data.