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if

The if statement is used for conditional execution of code blocks. It allows your program to make decisions and execute different code paths based on whether conditions are true or false.

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Basic If Statement

Simple conditional execution: 
age = 18

if (age >= 18) {
    println("You are an adult")
}

​
If-Else Statement

Execute different code blocks based on condition: 
score = 85

if (score >= 90) {
    println("Grade: A")
} else {
    println("Grade: B or lower")
}

​
If-Else If-Else Chain

Multiple conditions with different outcomes: 
temperature = 75

if (temperature > 80) {
    println("It's hot")
} else if (temperature > 60) {
    println("It's warm")
} else if (temperature > 40) {
    println("It's cool")
} else {
    println("It's cold")
}

​
Nested If Statements

If statements within other if statements: 
user = {
    "name": "Alice",
    "age": 25,
    "isActive": true,
    "hasPermission": true
}

if (user.isActive) {
    if (user.hasPermission) {
        if (user.age >= 18) {
            println("Access granted")
        } else {
            println("Access denied: Too young")
        }
    } else {
        println("Access denied: No permission")
    }
} else {
    println("Access denied: User inactive")
}

​
Complex Conditions

Using logical operators in conditions: 
username = "alice"
password = "secret123"
isLoggedIn = false

if (username == "alice" && password == "secret123") {
    isLoggedIn = true
    println("Login successful")
} else {
    println("Invalid credentials")
}

// Multiple conditions with OR
if (user.isAdmin || user.isModerator || user.hasSpecialAccess) {
    println("User has elevated privileges")
}

​
If with Function Calls

Using function results in conditions: 
soul isValidEmail(email) {
    return email.contains("@") && email.contains(".")
}

email = "user@example.com"

if (isValidEmail(email)) {
    println("Valid email address")
} else {
    println("Invalid email address")
}

​
If with Comparisons

Different comparison operators: 
a = 10
b = 20

if (a == b) {
    println("Equal")
} else if (a > b) {
    println("a is greater")
} else {
    println("b is greater")
}

// String comparisons
name1 = "Alice"
name2 = "Bob"

if (name1 != name2) {
    println("Different names")
}

​
If with Null Checks

Checking for null or undefined values: 
userData = getUserData()

if (userData != null) {
    if (userData.name != null && userData.name != "") {
        println("Welcome, " + userData.name)
    } else {
        println("Welcome, guest")
    }
} else {
    println("Unable to load user data")
}

​
If with Array/List Conditions

Checking array properties: 
items = getItems()

if (items != null && items.length() > 0) {
    println("Found " + items.length() + " items")
    
    for (item in items) {
        if (item.isValid()) {
            processItem(item)
        }
    }
} else {
    println("No items found")
}

​
If with Object Property Checks

Checking object properties: 
config = {
    "debug": true,
    "timeout": 5000,
    "retries": 3
}

if (config.debug) {
    println("Debug mode enabled")
}

if (config.timeout > 3000) {
    println("Long timeout configured")
}

​
If with Assignment

Assigning values based on conditions: 
userRole = "admin"
permissions = []

if (userRole == "admin") {
    permissions = ["read", "write", "delete", "admin"]
} else if (userRole == "user") {
    permissions = ["read", "write"]
} else {
    permissions = ["read"]
}

​
If with Early Returns

Using if statements for early function returns: 
soul processUser(user) {
    if (user == null) {
        return "Error: User is null"
    }
    
    if (!user.isActive) {
        return "Error: User is inactive"
    }
    
    if (user.age < 18) {
        return "Error: User is too young"
    }
    
    // Process user normally
    return "User processed successfully"
}

​
If with Error Handling

Conditional error handling: 
soul connectToDatabase(connectionString) {
    if (connectionString == null || connectionString == "") {
        throw("Invalid connection string")
    }
    
    connection = attemptConnection(connectionString)
    
    if (connection == null) {
        throw("Failed to connect to database")
    }
    
    return connection
}

​
If with Range Checks

Checking if values are within ranges: 
soul validateAge(age) {
    if (age < 0) {
        return "Age cannot be negative"
    } else if (age > 150) {
        return "Age seems unrealistic"
    } else if (age < 18) {
        return "Must be 18 or older"
    } else {
        return "Valid age"
    }
}

​
If with Type Checking

Conditional logic based on types: 
soul processValue(value) {
    if (typeof value == "string") {
        return "String: " + value.toUpperCase()
    } else if (typeof value == "number") {
        return "Number: " + (value * 2)
    } else if (typeof value == "boolean") {
        return "Boolean: " + (value ? "true" : "false")
    } else {
        return "Unknown type"
    }
}

​
If with Pattern Matching

Using if statements for pattern matching: 
soul handleResponse(response) {
    if (response.status == 200) {
        return processSuccessResponse(response)
    } else if (response.status == 404) {
        return handleNotFound()
    } else if (response.status >= 400 && response.status < 500) {
        return handleClientError(response)
    } else if (response.status >= 500) {
        return handleServerError(response)
    } else {
        return handleUnknownResponse(response)
    }
}

​
If with Guard Clauses

Using if statements as guard clauses: 
soul calculateDiscount(user, purchase) {
    // Guard clauses
    if (user == null) {
        return 0
    }
    
    if (purchase == null || purchase.amount <= 0) {
        return 0
    }
    
    if (!user.isActive) {
        return 0
    }
    
    // Main logic
    if (user.isPremium) {
        return purchase.amount * 0.15  // 15% discount
    } else if (purchase.amount > 100) {
        return purchase.amount * 0.10  // 10% discount
    } else {
        return purchase.amount * 0.05  // 5% discount
    }
}

​
Best Practices

  1. Use clear conditions: Make conditions easy to understand
  2. Avoid deep nesting: Use early returns or guard clauses
  3. Use meaningful variable names: Make conditions self-documenting
  4. Handle edge cases: Consider null/undefined values
  5. Use appropriate comparison operators: Choose the right operator for the context
// Good - clear and well-structured
soul authenticateUser(username, password) {
    if (username == null || username == "") {
        return { success: false, message: "Username required" }
    }
    
    if (password == null || password == "") {
        return { success: false, message: "Password required" }
    }
    
    user = findUserByUsername(username)
    
    if (user == null) {
        return { success: false, message: "User not found" }
    }
    
    if (!user.isActive) {
        return { success: false, message: "Account disabled" }
    }
    
    if (user.password != password) {
        return { success: false, message: "Invalid password" }
    }
    
    return { success: true, user: user }
}

// Better - with extracted validation functions
soul authenticateUser(username, password) {
    validationResult = validateCredentials(username, password)
    if (!validationResult.isValid) {
        return validationResult
    }
    
    user = findUserByUsername(username)
    userValidationResult = validateUser(user, password)
    
    return userValidationResult
}
The if statement is fundamental to controlling program flow and making decisions in Soul applications. Use it wisely to create clear, maintainable conditional logic.
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