What Is => Called and How Is It Used in C#

Question

I have seen => used in sample code, but I don't know what this operand is called. Because the term is just symbols, Google search is not very helpful.

Here is an example of its use:

var rolesAllowed = rolePermission.Where(permission => permission.Permissions.Any(p => Demand.HasFlag(p.Type))).ToList();

This question is different from the ones so brazenly marked as "duplicate". I was looking for the name of the expression so I could research how to use it. The so-called duplicate item was for someone who already knew that => was called a lambda expression.

I want to thank the people who took the time to read and understand the question, and post a quality response.

Take a look here http://www.pcreview.co.uk/forums/does-symbol-mean-t3532445.html — AliK, Apr 13 '13 at 20:01
Note that operators are searchable when you use quotes: `[C#] "=>"` — H H, Apr 13 '13 at 20:54

score 5 · Answer 1 · answered Apr 13 '13 at 19:59

It is called Lambda operator

To create a lambda expression, you specify input parameters (if any) on the left side of the lambda operator =>, and you put the expression or statement block on the other side. For example, the lambda expression x => x * x specifies a parameter that’s named x and returns the value of x squared.

Lambda expressions use special syntax. They allow functions to be used as data such as variables or fields. The lambda expression syntax uses the => operator. This separates the parameters and statement body of the anonymous function.

The => operator can be read as "goes to" and it is always used when declaring a lambda expression.

I've always pronounced it as 'such that', but 'goes to' is also very nice, so +1. — milan-j, Apr 13 '13 at 20:35

score 3 · Accepted Answer · answered Apr 13 '13 at 20:01

3

That is used to for lambda expressions. Essentially what that the Where function takes in is another function that iterates through the collection. The left side of the => defines the parameters and the right side is the actual function that gets run.

answered Apr 13 '13 at 20:01

Andy Meyers

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Great, thanks. So if I was to translate my sample code into an English sentence, it would be "Look for permissions in the Permissions class where that class is flagged as a specific type of permission, place it in a list, and assign it to the rolesAllowed variable"? – Rob Cole Apr 13 '13 at 20:07
That sounds like it describes the function above. – Andy Meyers Apr 13 '13 at 20:36

milan-j · Answer 3 · 2013-04-13T20:14:55.633

It is called lambda operator and it's the part of the lambda expression syntax.

Lambda expressions are very concise way to create anonymous methods.

Anonymous method example:

button1.Click += delegate(System.Object o, System.EventArgs e)
                   { MessageBox.Show("Click!"); };

The same code, but this time using lambda expression:

button1.Click += (o,e) => MessageBox.Show("Click!");

As shown, this syntax is a great shorthand notation for authoring anonymous methods, where a stack of arguments can be passed into a group of statements for processing. Any method in the .NET platform that takes a delegate object as an argument can be substituted with a related lambda expression, which will typically simplify your code base quite a bit.

score 1 · Answer 4 · answered Apr 13 '13 at 19:59

1

This is the lambda operator, it creates a lambda expression, which is like an anonymous method.

answered Apr 13 '13 at 19:59

Michael Greene

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score 1 · Answer 5 · edited May 23 '17 at 11:50

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=> is a lambda operator, check the link to read more.

Also check this answer for more details.

edited May 23 '17 at 11:50

Community

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answered Apr 13 '13 at 20:00

Mayank

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What Is => Called and How Is It Used in C#

5 Answers5