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

Concept Flow - List patterns

Create or have a list

↓

Start loop or access elements

↓

Check condition or pattern

Yes No↓

Process element

↓

Update index or move next

↩Back to loop start or end

This flow shows how we work with lists by looping through elements, checking conditions, processing items, and moving to the next until done.

Execution Sample

C Sharp (C#)

var numbers = new List<int> {1, 2, 3, 4, 5};
foreach (var n in numbers)
{
    if (n % 2 == 0)
        Console.WriteLine(n);
}

This code loops through a list of numbers and prints only the even ones.

Execution Table

Step	Current Element (n)	Condition (n % 2 == 0)	Action	Output
1	1	False	Skip
2	2	True	Print 2	2
3	3	False	Skip
4	4	True	Print 4	4
5	5	False	Skip
6	End of list	N/A	Stop loop

💡 Reached end of list, no more elements to process.

Variable Tracker

Variable	Start	After 1	After 2	After 3	After 4	After 5	Final
n	undefined	1	2	3	4	5	End

Key Moments - 3 Insights

Why does the loop skip printing some numbers?

Because the condition 'n % 2 == 0' is false for those numbers, so the action is to skip printing. See execution_table rows 1, 3, and 5.

What happens when the loop reaches the last element?

After processing the last element (5), the loop ends because there are no more elements. See execution_table row 6.

Why do we use 'foreach' instead of a 'for' loop here?

'foreach' automatically goes through each element in the list without needing an index, making the code simpler and less error-prone.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of 'n' at step 4?

A 2

B 3

C 4

D 5

💡 Hint

Check the 'Current Element (n)' column at step 4 in the execution_table.

At which step does the condition 'n % 2 == 0' become false for the first time?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at the 'Condition' column in execution_table rows 1 and 2.

If we add number 6 to the list, what will be the output at step 7?

A No output

B 6

C Error

D 5

💡 Hint

Even numbers print output; 6 is even. See pattern in execution_table outputs.

Concept Snapshot

List patterns in C#:
- Use 'foreach' to loop through list elements.
- Check conditions inside loop to filter or process items.
- Use 'if' to decide actions per element.
- Loop ends when all elements are processed.
- Simple and safe way to handle lists.

Full Transcript

This example shows how to use list patterns in C#. We start with a list of numbers. We loop through each number using 'foreach'. For each number, we check if it is even by using 'n % 2 == 0'. If true, we print the number. Otherwise, we skip it. The loop continues until all numbers are checked. This pattern helps process lists easily and clearly.