固定长度C#的字符串对象 [英] String Object with fixed length C#

问题描述

我有一堂课，我想使用固定大小的字符串.固定大小的原因是该类序列化"为文本文件具有固定长度的值.我想避免在foreach值中写一个保护子句，而由类来处理.

I have a class wherein I want to use Strings with a fixed size. The reason for the fixed size is that the class "serializes" into a textfile with values with a fixed length. I want to avoid to write foreach value a guard clause and instead have the class handle this.

所以我大约有30个属性，看起来像这样

So I have round about 30 properties which would look like this

    public String CompanyNumber
    {
        get 
        {
            return m_CompanyNumber.PadLeft(5, ' ');
        }
        set 
        {
            if (value.Length > 5) 
            {
                throw new StringToLongException("The CompanyNumber may only have 5 characters", "CompanyNumber");
            }
            m_CompanyNumber = value; 
        }
    } 

我想拥有一个可以自行处理的String.目前，我有以下内容:

I would like to have a String that handles this by itself. Currently I have the following:

public class FixedString
{
    String m_FixedString;

    public FixedString(String value)
    {
        if (value.Length > 5) 
        {
            throw new StringToLongException("The FixedString value may consist of 5 characters", "value");
        }
        m_FixedString= value;
    }

    public static implicit operator FixedString(String value)
    {
        FixedString fsv = new FixedString(value);
        return fsv;
    }

    public override string ToString()
    {
         return m_FixedString.PadLeft(5,' ');
    }
}

此解决方案的问题是我无法在编译时"设置字符串长度.

The problem I have with this solution is that I can't set the String length at "compile time".

如果最终看起来像这样，那将是理想的选择

It would be ideal if it would look something like this in the end

public FixedString<5> CompanyNumber { get; set; }

推荐答案

使 FixedString 使用大小作为构造函数参数，而不是值本身

Make FixedString take the size as a constructor parameter, but not the value itself

public class FixedString
{
   private string value;
   private int length;
   public FixedString(int length)
   {
      this.length = length;
   }

   public string Value 
   {
       get{ return value; }
       set
       {
            if (value.Length > length) 
            {
                 throw new StringToLongException("The field may only have " + length + " characters");
            }
           this.value = value; 
       }
   }
}

使用您的班级对其进行初始化，并在更改时设置 Value

Initilise it with your class, and just set the Value when it changes

public class MyClass
{
    private FixedString companyNumber = new FixedString(5);

    public string CompanyNumber
    {
        get{ return companyNumber.Value; }
        set{ companyNumber.Value = value; }
    }
}

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