🔁 C# If Statement / C# If…Else Statement – Complete Guide for Beginners

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🧲 Introduction – Why Learn C# If Statements?

In modern C# programming, conditional logic is essential. Whether you’re validating user input, deciding program flow, or building dynamic web pages, if statements empower your code to make decisions based on runtime data.

🎯 In this guide, you’ll learn:

• How to use if and if...else statements in C#
• Syntax rules and nesting best practices
• Real-world use cases with code walkthroughs
• Common pitfalls and tips for clean logic

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🔍 Core Concept – C# If Statement Explained

✅ Basic If Syntax

if (condition)
{
    // Executes if the condition is true
}

Example:

int age = 18;
if (age >= 18)
{
    Console.WriteLine("You are eligible to vote.");
}

🧵 Line-by-line Explanation:

• int age = 18; → Declares a variable with a value.
• if (age >= 18) → Evaluates the condition.
• Console.WriteLine(...) → Executes only if the condition is true.

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✅ C# If…Else Statement

if (condition)
{
    // Executes if condition is true
}
else
{
    // Executes if condition is false
}

Example:

int number = 5;
if (number % 2 == 0)
{
    Console.WriteLine("Even number.");
}
else
{
    Console.WriteLine("Odd number.");
}

🧵 Explanation:

• Checks if number is divisible by 2.
• Prints accordingly.

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🔁 Nested If Statements

if (condition1)
{
    if (condition2)
    {
        // Nested logic here
    }
}

Example:

int marks = 85;
if (marks >= 60)
{
    if (marks >= 80)
    {
        Console.WriteLine("Grade: A");
    }
    else
    {
        Console.WriteLine("Grade: B");
    }
}

📘 Best Practice: Avoid deep nesting by using logical operators.

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💡 Best Practices & Tips

💡 Tip: Always use curly braces {} – even for single statements.

⚠️ Pitfall: Avoid deep nesting; use else if for clarity.

📘 Best Practice: Keep conditions simple and readable. Break complex logic into helper methods.

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📊 Comparison Table: if vs if…else vs else if

Feature	if Only	if...else	else if Chain
Basic Usage	One condition	Two alternatives	Multiple conditions
Use Case	Execute when true	True or false logic	Multiple branching logic
Readability	High	Moderate	High (if structured well)

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🛠️ Real-World Use Cases

• ✅ Input validation: Checking if a user entered valid data.
• ✅ Business logic: Pricing tiers based on quantity.
• ✅ Web applications: Conditional rendering in Razor views.

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📌 Summary – Recap & Next Steps

🧵 Key Takeaways:

• if evaluates conditions; else handles alternatives.
• Use nesting sparingly; prefer else if for clarity.
• Follow formatting best practices for clean code.

⚙️ Real-world relevance: Mastery of if statements is essential for all C# developers—whether you’re building APIs, games in Unity, or enterprise apps.

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❓ FAQ Section

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❓ What is the difference between if and if...else in C#?
✅ if executes a block if a condition is true. if...else adds an alternative block for when the condition is false.

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❓ Can I use multiple if statements without else if?
✅ Yes, but it may lead to inefficient or unclear code. Prefer else if for mutually exclusive checks.

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❓ What happens if I forget the curly braces {} in if blocks?
✅ Only the next immediate statement is executed. This may cause bugs if not carefully structured.

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❓ How deep can I nest if statements in C#?
✅ Technically unlimited, but avoid nesting beyond 2-3 levels. Deep nesting reduces readability.

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❓ Are there alternatives to if...else in C#?
✅ Yes: switch-case for multiple options, ternary operator ?: for simple conditions.

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