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c#asp.net-mvcdelegates
yellowbowlmigration
yellowbowlmigration

Reputation: 143

what does this use of delegate mean?

I can't understand why delegate is used here:

List<string> temp_list = new List<string>();
string[] temp_array;
temp_array = Array.ConvertAll(arr_DL[m], delegate (int j) { return j.ToString(); });
temp_list.AddRange(temp_array.ToList());

the code is supposed to convert the array to list. Can someone help explain the use of delegate here?

Upvotes: 1

Views: 131

Answers (2)

Tetsuya Yamamoto
Tetsuya Yamamoto

Reputation: 24957

This part:

delegate (int j) { return j.ToString(); }

creates so-called "anonymous method" as second parameter TOutput, which used to convert int variable input into String then passes it into Array.ConvertAll() method. Anonymous methods used widely on C# 2.0, where in C# 3.0 they substituted with lambda expression like this:

delegate String output (int j);
String output = x => { x.ToString(); }

Reference: https://msdn.microsoft.com/en-us/library/bb882516.aspx

CMIIW.

Upvotes: 1

Dovydas Šopa
Dovydas Šopa

Reputation: 2300

That because it's the second parameter of ConvertAll method. It represent how each element in initial Array should be converted:

A Converter<TInput, TOutput> that converts each element from one type to another type.

So your delegate sais "convert each int j to string by performing j.ToString();"

Upvotes: 1

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