Array iteration with for and foreach in C Sharp (C#) - Step-by-Step Execution

Concept Flow - Array iteration with for and foreach

Start

↓

Choose iteration type

↓

Initialize index i=0

↓

Check i < array.Length?

No→End

↓

Access array[i

↓

Process element

↓

Increment i

Back to Check↓

Start at first element

↓

Get current element

↓

Process element

↓

Move to next element

↓

More elements?

No→End

↩Back to Check

This flow shows how a for loop uses an index to access array elements step-by-step, while foreach directly accesses each element one by one until all are processed.

Execution Sample

C Sharp (C#)

string[] fruits = {"apple", "banana", "cherry"};
for (int i = 0; i < fruits.Length; i++)
{
    Console.WriteLine(fruits[i]);
}

foreach (string fruit in fruits)
{
    Console.WriteLine(fruit);
}

This code prints each fruit in the array twice: first using a for loop with an index, then using a foreach loop that directly accesses each element.

Execution Table

Step	Loop Type	Index or Element	Condition	Action	Output
1	for	i=0	0 < 3 (true)	Print fruits[0] = "apple"	apple
2	for	i=1	1 < 3 (true)	Print fruits[1] = "banana"	banana
3	for	i=2	2 < 3 (true)	Print fruits[2] = "cherry"	cherry
4	for	i=3	3 < 3 (false)	Exit for loop
5	foreach	fruit="apple"	More elements? Yes	Print fruit	apple
6	foreach	fruit="banana"	More elements? Yes	Print fruit	banana
7	foreach	fruit="cherry"	More elements? Yes	Print fruit	cherry
8	foreach	End	More elements? No	Exit foreach loop

💡 for loop ends when i reaches array length; foreach ends when no more elements

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	After Step 6	After Step 7	Final
i	undefined	0	1	2	3	3	3	3	3
fruit	undefined	undefined	undefined	undefined	undefined	"apple"	"banana"	"cherry"	undefined

Key Moments - 3 Insights

Why does the for loop use an index variable 'i' but foreach does not?

The for loop uses 'i' to access elements by position (see execution_table rows 1-4). Foreach automatically accesses each element directly without needing an index (rows 5-8).

What happens when the for loop index 'i' equals the array length?

When 'i' equals the array length (3), the condition 'i < fruits.Length' becomes false (row 4), so the loop stops to avoid accessing outside the array.

Can you modify the array elements inside foreach?

No, foreach provides a read-only copy of each element (like in rows 5-7). To modify elements, use a for loop with an index.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of 'i' at Step 3?

A 2

B 3

C 1

D 0

💡 Hint

Check the 'Index or Element' column for Step 3 in the execution_table.

At which step does the foreach loop stop iterating?

A Step 6

B Step 7

C Step 8

D Step 4

💡 Hint

Look for the step where 'More elements? No' appears in the Condition column for foreach.

If the array had 4 elements instead of 3, how many times would the for loop run?

A 3 times

B 4 times

C 5 times

D Depends on the elements

💡 Hint

The for loop runs while i < array.Length; see how length controls iterations in execution_table rows 1-4.

Concept Snapshot

for loop: use index i from 0 to array.Length-1 to access elements
foreach loop: directly access each element without index
for allows modifying elements; foreach is read-only
both loop through all elements in order
for needs condition check; foreach ends when no more elements

Full Transcript

This visual execution shows how to loop through an array in C# using for and foreach. The for loop uses an index variable i starting at 0 and runs while i is less than the array length. Each iteration prints the element at fruits[i]. When i reaches the length, the loop stops to avoid errors. The foreach loop automatically accesses each element one by one, printing each fruit until no elements remain. Variables i and fruit change as the loops run. Key points include that for loops use an index and can modify elements, while foreach loops provide read-only access. The execution table tracks each step, showing conditions, actions, and outputs. This helps beginners see exactly how the loops work step-by-step.