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Delegates and Lambda Expressions in C# 3.0
Lambda expressions are functions with a different syntax that enables them to be used in an expression
context instead of the usual object-oriented method of being a member of a class. With a single syntax,
we can express a method definition, declaration, and the invocation of delegate to execute it, just an
anonymous methods can, but with a more terse syntax.
A projection is a lambda expression that translates on type into another.
A lambda expreesion looks like this:
j => j*50
The following code snippets demonstrates the importance of lambda expressions. It would help us
understand how can one implement code in C# 1.0/2.0 without lambda expressions.
C# 1.0 way of implementation
public delegate int IncreaseByANumber(int j);
static public int MultiplyByANumber(int j)
{
return j * 50;
}
public static void InvokeCSharp1_0()
{
IncreaseByANumber increase =
new IncreaseByANumber(MultiplyByANumber);
Console.WriteLine("Result from C# 1.0 way of implementation= " + increase(20));
}
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C# 2.0 way of implementation
public delegate int IncreaseByANumber(int j);
public static void InvokeCSharp2_0()
{
IncreaseByANumber increase =
new IncreaseByANumber(
delegate(int j)
{
return j * 50;
}
);
Console.WriteLine("Result from C# 2.0 way of implementation= " + increase(20));
}
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C# 3.0 way of implementation
public delegate int IncreaseByANumber(int j);
public static void InvokeCSharp3_0()
{
IncreaseByANumber increase = j => j * 50;
Console.WriteLine("Result from C# 3.0 way of implementation= " + increase(20));
}
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Downloads
The sample code can be downloaded from below link. The code is complied with Microsoft Visual C# 2008.
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