Lambda Expressions in C#
Introduction:
Lambda expressions are nothing but an anonymous function. i.e. Lambda Expressions have no name, no access modifiers, and no return values.
The syntax of Lambda expression is as below:
argument => expression;
=> is called Lambda operator and we read it as "goes to".
This is equivalent of writing as below:
static public returnType functionName(argument)
{
expression;
}
Compare both these methods. The Lambda expression syntax has no name, no access modifiers, and no return values.
If we have no arguments then, the syntax is
() => expression.
if we have multiple arguments, then
(arg1, arg2, ...) = > expression.
Example:
In the below example, which calculates square of a function, is a Lambda Expression. The second snippet uses normal function.
Lambda Expressions:
Func<int,int> sqr = x => x * x;
Console.WriteLine(sqr(5));
Normal Function:
Console.WriteLine(square(5));
static int square(int x)
{
return x * x;
}
Hence, we use Lambda expression for convenience and readability.
Practical usage of Lambda Expression:
Lambda Expressions are very useful when we use Collections functions such as Find, FindAll.
These methods take Predicate as arguments, which is a function that contains a condition on which the collection function could apply.
If we don't use Lamda Expressions, the code looks a tad messy.
Consider the below example; I have created a list of integers. And we shall use FindAll(). We can create the Predicate functions and pass it to FindAll() method.
List<int> numList = new List<int>()
{
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
};
var listOfAbovefive = numList.FindAll(AboveFiveCond);
static bool AboveFiveCond(int i)
{
return i > 5;
}
foreach (int num in listOfAbovefive)
{
Console.WriteLine(num);
}
However, if we use Lambda Expression, the code looks cleaner.
List<int> numList = new List<int>()
{
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
};
var listOfAbovefive = numList.FindAll(x => x > 5);
foreach (int num in listOfAbovefive)
{
Console.WriteLine(num);
}
