Expression-bodied lambdas in C Sharp (C#) - Step-by-Step Execution

Concept Flow - Expression-bodied lambdas

Define lambda with => expression

↓

Invoke lambda

↓

Evaluate expression

↓

Return result

An expression-bodied lambda uses => to define a function with a single expression that returns a value immediately.

Execution Sample

C Sharp (C#)

Func<int, int> square = x => x * x;
int result = square(3);
Console.WriteLine(result);

Defines a lambda that squares a number and prints the result of squaring 3.

Execution Table

Step	Action	Expression Evaluated	Result
1	Define lambda 'square' as x => x * x	x * x	Lambda stored, no output
2	Call square(3)	3 * 3	9
3	Print result	Console.WriteLine(9)	Outputs 9

💡 Program ends after printing the result 9

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
square	null	lambda function (x => x * x)	lambda function	lambda function
result	undefined	undefined	9	9

Key Moments - 2 Insights

Why does the lambda not need curly braces or a return statement?

Because expression-bodied lambdas use a single expression after => which automatically returns its value, as shown in step 1 and 2 of the execution_table.

What happens when we call square(3)?

The expression x * x is evaluated with x=3, resulting in 9, as shown in step 2 of the execution_table.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of 'result' after step 2?

A undefined

B 9

C 3

D null

💡 Hint

Check the 'Result' column in row for step 2 in execution_table.

At which step is the lambda function assigned to 'square'?

A Step 3

B Step 2

C Step 1

D Before Step 1

💡 Hint

Look at the 'Action' column in execution_table for when 'square' is defined.

If we changed the lambda to x => x + 1, what would be the output at step 3?

A 4

B 9

C 3

D 1

💡 Hint

Consider the expression evaluated in step 2 and how it affects the printed result in step 3.

Concept Snapshot

Expression-bodied lambdas use => followed by a single expression.
They automatically return the expression's value.
No curly braces or return keyword needed.
Example: Func<int,int> square = x => x * x;
Call like: square(3) returns 9.

Full Transcript

This example shows how expression-bodied lambdas work in C#. First, we define a lambda named 'square' that takes an integer x and returns x multiplied by itself. This is done using the => syntax with a single expression 'x * x'. When we call square(3), the expression evaluates to 9. Finally, we print the result 9 to the console. The lambda does not need curly braces or a return statement because the expression after => is automatically returned.