Loop

What is a Loop?

Syntax used when you want to execute the same code multiple times. Useful in Unity for spawning multiple monsters or checking all values in an array.

Increment/Decrement Operators

Increment Operator (++)

int count = 0;
count++;  // Same as count = count + 1 (result: 1)
++count;  // Same as count = count + 1 (result: 2)

Decrement Operator (--)

int count = 10;
count--;  // Same as count = count - 1 (result: 9)
--count;  // Same as count = count - 1 (result: 8)

Compound Assignment Operators

Simple way to add or subtract values from variables.

int score = 100;

score += 10;  // score = score + 10 (result: 110)
score -= 5;   // score = score - 5 (result: 105)
score *= 2;   // score = score * 2 (result: 210)
score /= 3;   // score = score / 3 (result: 70)
score %= 4;   // score = score % 4 (result: 2)

while Statement

Continues to loop while condition is true.

Basic Syntax

while (condition)
{
    // Code to execute
}

Example

int count = 0;

while (count < 10)
{
    Debug.Log("Spawn Minion");
    count++;  // Increase count by 1
}
// "Spawn Minion" is output 10 times

Notes

• If condition is always true, infinite loop can occur
• Must have code that makes condition false

for Statement

A loop that writes initial value, condition, and increment in one line.

Basic Syntax

for (initial value; condition; increment)
{
    // Code to execute
}

Example

for (int i = 0; i < 10; i++)
{
    Debug.Log("Spawn Minion " + i);
}
// Outputs "Spawn Minion 0" through "Spawn Minion 9"

Execution Order

1. int i = 0 - Set initial value (executes once)
2. i < 10 - Check condition
3. If true, execute code
4. i++ - Increase i by 1
5. Return to step 2 and repeat

Using with Arrays

Using Array's Length

int[] myArray = { 0, 3, 6, 9, 12, 15, 18, 21, 24, 27 };

for (int i = 0; i < myArray.Length; i++)
{
    Debug.Log(myArray[i]);  // Output all array values
}

Important: Arrays use Length to check count.

Using List's Count

List<int> myList = new List<int>() { 4, 6, 9 };

for (int i = 0; i < myList.Count; i++)
{
    Debug.Log(myList[i]);  // Output all list values
}

Important: Lists use Count to check count. (Not Length!)

foreach Statement

Used to iterate through all elements of arrays or lists. Useful when index is not needed.

Basic Syntax

foreach (type variableName in collection)
{
    // Code to execute
}

Example

List<string> names = new List<string>() { "Alice", "Bob", "Charlie" };

foreach (string name in names)
{
    Debug.Log(name);  // Outputs "Alice", "Bob", "Charlie" in order
}

Advantages of foreach

• No need to manage index
• Code is concise
• No worry about going out of array bounds

Loop Comparison

Loop	When to Use	Features
while	When only condition exists	Repeats until condition becomes false
for	When number of iterations is known	Initial value, condition, increment in one line
foreach	When iterating through all elements	Simple without index

Practical Usage Examples

Spawning Monsters

void Start()
{
    for (int i = 0; i < 10; i++)
    {
        Debug.Log("Spawn Minion " + i + "!");
    }
}

Checking Score Array

int[] scores = { 100, 200, 150, 300 };

for (int i = 0; i < scores.Length; i++)
{
    if (scores[i] > 200)
    {
        Debug.Log("High score: " + scores[i]);
    }
}

Outputting Inventory Items

List<string> inventory = new List<string>() { "Sword", "Shield", "Potion" };

foreach (string item in inventory)
{
    Debug.Log("Inventory: " + item);
}

Notes

1. Beware of infinite loops: Be careful that while condition doesn't always stay true
2. Array bounds: Use i < array.Length in for loops to avoid going out of bounds
3. Array uses Length, List uses Count: Be careful not to confuse them

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