for

The for loop is a control flow statement that allows code to be executed repeatedly based on a condition. Soul supports the classic C-style for loop with initialization, condition, and increment components.

Basic For Loop

The standard for loop syntax with initialization, condition, and increment:

for (i = 0; i < 5; i++) {
    println("Iteration: " + i)
}
// Output: 0, 1, 2, 3, 4

For Loop Components

A for loop consists of three parts:

for (initialization; condition; increment) {
    // Loop body
}

// Example with explicit parts
for (counter = 1; counter <= 10; counter++) {
    println("Counter: " + counter)
}

Different Initialization Patterns

Various ways to initialize the loop variable:

// Start from 0
for (i = 0; i < 5; i++) {
    println("i: " + i)
}

// Start from 1
for (i = 1; i <= 5; i++) {
    println("i: " + i)
}

// Start from a specific value
for (i = 10; i >= 0; i--) {
    println("Countdown: " + i)
}

Different Increment Patterns

Various ways to modify the loop variable:

// Increment by 1
for (i = 0; i < 10; i++) {
    println(i)
}

// Increment by 2
for (i = 0; i < 10; i += 2) {
    println("Even: " + i)
}

// Decrement
for (i = 10; i > 0; i--) {
    println("Countdown: " + i)
}

// Multiply by 2
for (i = 1; i < 100; i *= 2) {
    println("Power of 2: " + i)
}

For Loops with Arrays

Iterating through arrays using index:

numbers = [10, 20, 30, 40, 50]

for (i = 0; i < numbers.length(); i++) {
    println("Index " + i + ": " + numbers[i])
}

For Loops with Strings

Iterating through string characters:

text = "Hello"

for (i = 0; i < text.length(); i++) {
    println("Character " + i + ": " + text[i])
}

Nested For Loops

For loops can be nested for multi-dimensional processing:

// Multiplication table
for (i = 1; i <= 5; i++) {
    for (j = 1; j <= 5; j++) {
        result = i * j
        print(result + "\t")
    }
    println("")  // New line after each row
}

For Loops with Complex Conditions

Using complex conditions and multiple variables:

// Multiple conditions
for (i = 0, j = 10; i < j; i++, j--) {
    println("i: " + i + ", j: " + j)
}

// Complex condition
for (i = 0; i < 100 && isPrime(i); i++) {
    println("Prime: " + i)
}

For Loops with Break and Continue

Controlling loop execution:

// Using break
for (i = 0; i < 10; i++) {
    if (i == 5) {
        break  // Exit loop when i equals 5
    }
    println("i: " + i)
}

// Using continue
for (i = 0; i < 10; i++) {
    if (i % 2 == 0) {
        continue  // Skip even numbers
    }
    println("Odd: " + i)
}

For Loops in Data Processing

Common patterns for processing data:

// Sum calculation
numbers = [1, 2, 3, 4, 5]
sum = 0

for (i = 0; i < numbers.length(); i++) {
    sum += numbers[i]
}
println("Sum: " + sum)

// Finding maximum
values = [23, 45, 12, 67, 34]
max = values[0]

for (i = 1; i < values.length(); i++) {
    if (values[i] > max) {
        max = values[i]
    }
}
println("Maximum: " + max)

For Loops with Functions

Calling functions within for loops:

soul processItem(item, index) {
    return "Item " + index + ": " + item.toUpperCase()
}

items = ["apple", "banana", "cherry"]

for (i = 0; i < items.length(); i++) {
    processed = processItem(items[i], i)
    println(processed)
}

For Loops with Objects

Iterating through object properties using indices:

user = {
    "name": "Alice",
    "age": 30,
    "email": "alice@example.com"
}

keys = user.keys()
for (i = 0; i < keys.length(); i++) {
    key = keys[i]
    value = user[key]
    println(key + ": " + value)
}

Infinite For Loops

Creating infinite loops (use with caution):

// Infinite loop - be careful!
for (;;) {
    input = readInput()
    if (input == "quit") {
        break
    }
    processInput(input)
}

For Loops with Error Handling

Handling errors within for loops:

urls = ["http://example1.com", "http://example2.com", "http://example3.com"]

for (i = 0; i < urls.length(); i++) {
    try {
        response = fetchData(urls[i])
        processResponse(response)
    } catch (error) {
        println("Error fetching " + urls[i] + ": " + error)
        continue  // Skip to next URL
    }
}

Performance Considerations

Optimizing for loop performance:

// Cache array length
items = getItems()
length = items.length()

for (i = 0; i < length; i++) {
    processItem(items[i])
}

// Avoid expensive operations in loop condition
for (i = 0; i < items.length(); i++) {  // length() called each iteration
    processItem(items[i])
}

Best Practices

Use meaningful variable names: index instead of i when clarity is important
Cache array lengths: Store length in a variable for better performance
Use appropriate increment: Choose the right increment pattern for your needs
Handle edge cases: Check for empty arrays or invalid indices

// Good - clear and efficient
soul processUserData(users) {
    userCount = users.length()
    
    for (index = 0; index < userCount; index++) {
        user = users[index]
        
        if (user.isActive) {
            processActiveUser(user)
        }
    }
}

// Better - with validation
soul processUserData(users) {
    if (users == null || users.length() == 0) {
        return
    }
    
    for (index = 0; index < users.length(); index++) {
        user = users[index]
        if (user != null && user.isActive) {
            processActiveUser(user)
        }
    }
}

The for loop is essential for controlled iteration and is particularly useful when you need access to the current index or want precise control over the iteration process.

CLI Usage

Modules

Syntaxes

for

for

Basic For Loop

For Loop Components

Different Initialization Patterns

Different Increment Patterns

For Loops with Arrays

For Loops with Strings

Nested For Loops

For Loops with Complex Conditions

For Loops with Break and Continue

For Loops in Data Processing

For Loops with Functions

For Loops with Objects

Infinite For Loops

For Loops with Error Handling

Performance Considerations

Best Practices

​for

​Basic For Loop

​For Loop Components

​Different Initialization Patterns

​Different Increment Patterns

​For Loops with Arrays

​For Loops with Strings

​Nested For Loops

​For Loops with Complex Conditions

​For Loops with Break and Continue

​For Loops in Data Processing

​For Loops with Functions

​For Loops with Objects

​Infinite For Loops

​For Loops with Error Handling

​Performance Considerations

​Best Practices

for

Basic For Loop

For Loop Components

Different Initialization Patterns

Different Increment Patterns

For Loops with Arrays

For Loops with Strings

Nested For Loops

For Loops with Complex Conditions

For Loops with Break and Continue

For Loops in Data Processing

For Loops with Functions

For Loops with Objects

Infinite For Loops

For Loops with Error Handling

Performance Considerations

Best Practices