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

Concept Flow - Constant patterns

Start

↓

Match value with constant pattern

↓

End

The program checks if a value matches a constant pattern. If yes, it runs matched code; if no, it runs other code or skips.

Execution Sample

C Sharp (C#)

int number = 5;
if (number is 5)
{
    Console.WriteLine("Number is five");
}
else
{
    Console.WriteLine("Number is not five");
}

Checks if number equals 5 using a constant pattern and prints a message accordingly.

Execution Table

Step	Variable 'number'	Condition 'number is 5'	Branch Taken	Output
1	5	True	If branch	Number is five
2	5	N/A	End	Program ends

💡 Condition is true at step 1, so if branch runs and program ends after.

Variable Tracker

Variable	Start	After Step 1	Final
number	5	5	5

Key Moments - 2 Insights

Why does the code use 'is 5' instead of '== 5'?

The 'is 5' is a constant pattern that checks if the value matches 5 exactly, similar to '== 5'. It is used in pattern matching syntax. See execution_table step 1 where condition is evaluated.

What happens if 'number' is not 5?

If 'number' is not 5, the condition 'number is 5' is false and the else branch runs. This is shown by the 'No' path in concept_flow.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of 'number' at step 1?

A 5

B 0

C null

D 10

💡 Hint

Check the 'Variable number' column at step 1 in execution_table.

At which step does the program decide to print 'Number is five'?

A Step 2

B No step, it never prints

C Step 1

D Before step 1

💡 Hint

Look at the 'Branch Taken' and 'Output' columns in execution_table.

If 'number' was 3 instead of 5, what would change in the execution_table?

A Condition would be true and if branch runs

B Condition would be false and else branch runs

C Variable 'number' would be 5

D Program would crash

💡 Hint

Refer to concept_flow where 'No' branch leads to other code.

Concept Snapshot

Constant patterns check if a value equals a fixed constant.
Syntax: 'variable is constantValue'.
If true, matched code runs.
If false, else or other code runs.
Useful for clear, readable condition checks.

Full Transcript

This example shows how constant patterns work in C#. The program sets a variable 'number' to 5. It then checks if 'number is 5' using a constant pattern. If true, it prints 'Number is five'. Otherwise, it prints 'Number is not five'. The flow starts by checking the condition. Since number is 5, the condition is true and the if branch runs. The variable 'number' stays 5 throughout. If the number was different, the else branch would run. Constant patterns are a simple way to compare values in pattern matching syntax.