Property patterns in C Sharp (C#) - Step-by-Step Execution

Concept Flow - Property patterns

Start with an object

↓

Check property values

↓

Match pattern?

↓

Execute true

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End

Property patterns check if an object's properties match specified values, then decide the flow based on the match.

Execution Sample

C Sharp (C#)

record Person(string Name, int Age);

var person = new Person("Alice", 30);

if (person is { Name: "Alice", Age: 30 })
    Console.WriteLine("Match found");
else
    Console.WriteLine("No match");

This code checks if the person object has Name "Alice" and Age 30, then prints a message accordingly.

Execution Table

Step	Expression Evaluated	Property Checked	Value Found	Condition Result	Branch Taken	Output
1	person is { Name: "Alice", Age: 30 }	Name	"Alice"	Matches	Continue
2	person is { Name: "Alice", Age: 30 }	Age	30	Matches	Continue
3	if condition	N/A	N/A	True	True branch	Match found

💡 All property checks matched, so the if condition is true and 'Match found' is printed.

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
person.Name	"Alice"	"Alice"	"Alice"	"Alice"
person.Age	30	30	30	30

Key Moments - 2 Insights

Why does the pattern check both Name and Age properties?

Because the pattern requires all specified properties to match for the condition to be true, as shown in execution_table rows 1 and 2.

What happens if one property does not match?

The condition becomes false and the else branch runs, as the pattern requires all properties to match (see exit_note).

Visual Quiz - 3 Questions

Look at the execution table, what is the value of person.Name at Step 1?

A "Bob"

B "Alice"

C null

D 30

💡 Hint

Check the 'Value Found' column at Step 1 in the execution_table.

At which step does the condition become true?

A Step 1

B Step 2

C Step 3

D Condition never becomes true

💡 Hint

Look at the 'Condition Result' and 'Branch Taken' columns in the execution_table.

If person.Age was 25 instead of 30, what would happen?

A The condition would be false

B The program would crash

C The condition would be true

D The output would be 'Match found'

💡 Hint

Refer to key_moments about property mismatch and exit_note.

Concept Snapshot

Property patterns check if an object's properties match given values.
Syntax: obj is { Prop1: val1, Prop2: val2 }
All specified properties must match for true.
Used in if, switch, or expressions.
Simplifies checking multiple properties at once.

Full Transcript

This example shows how property patterns work in C#. We start with an object 'person' having properties Name and Age. The pattern checks if person.Name equals "Alice" and person.Age equals 30. Each property is checked step-by-step. If all match, the condition is true and the program prints 'Match found'. If any property does not match, the condition is false and the else branch runs. This helps write clear code that checks multiple properties easily.