I have a list where I want to remove last comma from every list item, what is the best way to do it in c# linq

    var mylist = new List<colors>{
      new Color{
        Id=1, 
        Name="red,blue,green,orange,"
      },
      new Color{
        Id=2, 
        Name="purple,sky blue, pink, red,"},
      new Color{
        Id=3, 
        Name="green, yellow, black,"
      },
      new Color{
        Id=4, 
        Name="white,black,red, blue,"
      }
}

Is there any way to remove last comma from all items in a one go by using linq c#?

CodePudding user response：

Linq is excelent for quering data not for modifying; that's why I suggest a good old for loop:

for (int i = 0; i < myList.Count;   i) 
  myList[i].Name = myList[i].Name.TrimEnd(',');

or if Name is init-only and we have to recreate Color:

for (int i = 0; i < myList.Count;   i) 
  myList[i] = new Color() {
    Id   = myList[i].Id, 
    Name = myList[i].Name.TrimEnd(',')
  }

Technically, you can use Linq

myList = myList
  .Select(color => new Color() {
    Id   = color.Id,
    Name = color.Name.TrimEnd(',')
  })
  .ToList();

but it's overshoot

CodePudding user response：

Maybe you can change your class Color definition as follows:

class Color
{
    public int Id{get;set;}
    private string _name;
    public string Name{
        get{
            return _name;
        }
        set{
            _name = value.TrimEnd(',');
        }
    }
}

then when you create a list, the comma is auto removed, no need to do anything:

var mylist = new List<colors>{
  new Color{
    Id=1, 
    Name="red,blue,green,orange,"
  },
  new Color{
    Id=2, 
    Name="purple,sky blue, pink, red,"},
  new Color{
    Id=3, 
    Name="green, yellow, black,"
  },
  new Color{
    Id=4, 
    Name="white,black,red, blue,"
  }
}

Approach 1: add constructor to your class

public class Color
{
    public Color()
    {
    
    }
    
    public Color(Color source)
    {
        this.Id = source.Id;
        this.Name = source.Name.TrimEnd(',');
    }
    
    public int Id{get;set;}
    public string Name{get;set;}
}
void Main()
{
    var mylist = new List<Color>{
          new Color{
            Id=1, 
            Name="red,blue,green,orange,"
          },
          new Color{
            Id=2, 
            Name="purple,sky blue, pink, red,"},
          new Color{
            Id=3, 
            Name="green, yellow, black,"
          },
          new Color{
            Id=4, 
            Name="white,black,red, blue,"
          }
    };  

    var res = from c in mylist
              select new Color(c);
    Console.Write(res);
}

Approach 2: add a RemoveComma() method to your class

public class Color
{
    public int Id{get;set;}
    public string Name{get;set;}
    
    public Color RemoveComma()
    {
        this.Name = this.Name.TrimEnd(',');
        return this;
    }
}
void Main()
{
    var mylist = new List<Color>{
          new Color{
            Id=1, 
            Name="red,blue,green,orange,"
          },
          new Color{
            Id=2, 
            Name="purple,sky blue, pink, red,"},
          new Color{
            Id=3, 
            Name="green, yellow, black,"
          },
          new Color{
            Id=4, 
            Name="white,black,red, blue,"
          }
    };  

    var res = from c in mylist
              select c.RemoveComma();
    Console.Write(res);
}

Approach 3: if you dont want to modify the Color class, define a extension method

public class Color
{
    public int Id{get;set;}
    public string Name{get;set;}
}

public static class ColorExtensions
{
    public static Color RemoveComma(this Color c)
    {
        c.Name = c.Name.TrimEnd(',');
        return c;
    }
}

void Main()
{
    var mylist = new List<Color>{
          new Color{
            Id=1, 
            Name="red,blue,green,orange,"
          },
          new Color{
            Id=2, 
            Name="purple,sky blue, pink, red,"},
          new Color{
            Id=3, 
            Name="green, yellow, black,"
          },
          new Color{
            Id=4, 
            Name="white,black,red, blue,"
          }
    };  

    var res = from c in mylist
              select c.RemoveComma();
    Console.Write(res);
}