Alternative to using ref in foreach?

user_6263317 0
Viewed 18801

I have a modifying method with a signature like

private bool Modify(ref MyClass obj);

that will make modifications to obj and indicate succes with it's return value. Modify is not reassigning the reference (I know that this wouldn't work), just modifying instance fields, so I want to use it to do something like the following:

foreach(MyClass obj in myList)
{
    bool success = Modify(obj);
    // do things depending on success
}

I am running into a problem compiling as obj is "not being passed with the ref keyword". However, if I put the ref keyword in like so:

bool success = Modify(ref obj);

I get "cannot use obj as a ref/out because it is a 'foreach iteration variable". I understand that foreach uses an immutable iterator and that's why this doesn't work.

My question is what is the easiest alternative to make something like this work?

I have tried using 

foreach(int i = 0; i < myList.Count; i++)
{
    bool success = Modify(ref myList[i]);
    // do things depending on success
}

but they I get "a property or indexer may not be passed as an out of ref parameter".

Thanks your help.

ref foreach c#
4 Answers

use a temp variable to bypass the message

foreach(MyClass obj in myList)
{
    MyClass objTemp = obj;
    bool success = Modify(ref objTemp);
    // do things depending on success
}

private MyMethod(ref MyClass instance)
{
    instance.MyProperty = ...
}
user_35480890

It is solved by using LINQ.

My Code:

    private static List<string> _test = new List<string>();

    public List<string> Test { get => _test; set => _test = value; }


    static void Main(string[] args)
    {
        string numString = "abcd";

        _test.Add("ABcd");
        _test.Add("bsgd");

        string result = _test.Where(a => a.ToUpper().Equals(numString.ToUpper()) == true).FirstOrDefault();

        Console.WriteLine(result + " linq");
    }
user_111953090
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