If statement execution flow in C Sharp (C#) - Mini Project: Build & Apply

If Statement Execution Flow

📖 Scenario: You are creating a simple program to check the temperature and give advice on what to wear. This helps you understand how decisions are made in a program using if statements.

🎯 Goal: Build a program that uses if statements to check the temperature and print the right clothing advice.

📋 What You'll Learn

Create an integer variable temperature with the value 15

Create an integer variable coldThreshold with the value 10

Use an if statement to check if temperature is less than coldThreshold

Print "Wear a coat" if the temperature is cold

Print "No coat needed" if the temperature is not cold

💡 Why This Matters

🌍 Real World

Checking weather conditions to give clothing advice is common in apps and websites.

💼 Career

Understanding if statements is essential for making decisions in any software development job.

1

Create the temperature variable

Create an integer variable called temperature and set it to 15.

C Sharp (C#)

// Your code here

Hint

Use int temperature = 15; to create the variable.

2

Create the cold threshold variable

Create an integer variable called coldThreshold and set it to 10.

C Sharp (C#)

int temperature = 15;
// Your code here

Hint

Use int coldThreshold = 10; to create the variable.

3

Write the if statement to check temperature

Write an if statement that checks if temperature is less than coldThreshold. Inside the if, write Console.WriteLine("Wear a coat");. Use else to write Console.WriteLine("No coat needed"); when the temperature is not cold.

C Sharp (C#)

int temperature = 15;
int coldThreshold = 10;
// Your code here

Hint

Use if (temperature < coldThreshold) and else blocks with Console.WriteLine.

4

Print the result

Run the program and print the output to see the advice based on the temperature.

C Sharp (C#)

int temperature = 15;
int coldThreshold = 10;
if (temperature < coldThreshold)
{
    Console.WriteLine("Wear a coat");
}
else
{
    Console.WriteLine("No coat needed");
}
// Your code here

Hint

The program should print "No coat needed" because 15 is not less than 10.

Practice

1. What does an if statement do in C#?

easy

A. It defines a new variable.

B. It repeats code multiple times.

C. It chooses which code to run based on a condition.

D. It stops the program immediately.

Solution

1. Step 1: Understand the purpose of if

   An if statement checks a condition to decide which code runs next.

2. Step 2: Compare options

   Only It chooses which code to run based on a condition. describes choosing code based on a condition, which matches the if statement's role.

3. Final Answer:

   It chooses which code to run based on a condition. -> Option C

4. Quick Check:

   if chooses code path = C [OK]

Hint: If checks true/false to pick code path quickly [OK]

Common Mistakes:

• Confusing if with loops
• Thinking if defines variables
• Believing if stops program

2. Which of these is the correct syntax for an if statement in C#?

easy

A. if (x > 5) Console.WriteLine("Yes") end

B. if x > 5 then Console.WriteLine("Yes")

C. if x > 5: Console.WriteLine("Yes")

D. if (x > 5) { Console.WriteLine("Yes"); }

Solution

1. Step 1: Review C# if syntax

   C# requires parentheses around the condition and braces for the block.

2. Step 2: Check each option

   if (x > 5) { Console.WriteLine("Yes"); } uses parentheses and braces correctly; others use wrong keywords or punctuation.

3. Final Answer:

   if (x > 5) { Console.WriteLine("Yes"); } -> Option D

4. Quick Check:

   Correct C# if syntax = D [OK]

Hint: Remember: if(condition) { code } in C# [OK]

Common Mistakes:

• Omitting parentheses around condition
• Using Python or other language syntax
• Missing braces for code block

3. What will this code print?

int x = 10;
if (x < 5) {
  Console.WriteLine("Less");
} else {
  Console.WriteLine("More or equal");
}

medium

A. Less

B. More or equal

C. Nothing

D. Error

Solution

1. Step 1: Evaluate the condition

   The condition x < 5 is false because x is 10.

2. Step 2: Determine which block runs

   Since the condition is false, the else block runs, printing "More or equal".

3. Final Answer:

   More or equal -> Option B

4. Quick Check:

   Condition false -> else runs = A [OK]

Hint: If false, else block runs [OK]

Common Mistakes:

• Thinking if block runs when false
• Ignoring else block
• Confusing < with >

4. Find the error in this code:

int num = 7;
if num > 5 {
  Console.WriteLine("Big");
} else {
  Console.WriteLine("Small");
}

medium

A. Missing parentheses around the condition

B. Missing semicolon after if

C. Wrong keyword else

D. Variable num not declared

Solution

1. Step 1: Check if statement syntax

   C# requires parentheses around the condition in an if statement.

2. Step 2: Identify the error

   The code has if num > 5 { without parentheses, causing a syntax error.

3. Final Answer:

   Missing parentheses around the condition -> Option A

4. Quick Check:

   Parentheses needed in if condition = A [OK]

Hint: Always put condition inside parentheses in if [OK]

Common Mistakes:

• Forgetting parentheses in if
• Adding semicolon after if line
• Misusing else keyword

5. You want to print "Positive", "Negative", or "Zero" based on an integer n. Which code correctly uses if statements to do this?

hard

A. if (n > 0) { Console.WriteLine("Positive"); } else if (n < 0) { Console.WriteLine("Negative"); } else { Console.WriteLine("Zero"); }

B. if (n > 0) Console.WriteLine("Positive"); if (n < 0) Console.WriteLine("Negative"); else Console.WriteLine("Zero");

C. if (n > 0) { Console.WriteLine("Positive"); } else { if (n > 0) { Console.WriteLine("Negative"); } else { Console.WriteLine("Zero"); } }

D. if (n > 0) { Console.WriteLine("Positive"); } else if (n <= 0) { Console.WriteLine("Zero"); } else { Console.WriteLine("Negative"); }

Solution

1. Step 1: Understand the logic needed

   We need to check if n is greater than 0, less than 0, or exactly 0.

2. Step 2: Analyze each option

   if (n > 0) { Console.WriteLine("Positive"); } else if (n < 0) { Console.WriteLine("Negative"); } else { Console.WriteLine("Zero"); } correctly uses if, else if, and else to cover all cases without overlap or missing conditions.

3. Final Answer:

   if (n > 0) { Console.WriteLine("Positive"); } else if (n < 0) { Console.WriteLine("Negative"); } else { Console.WriteLine("Zero"); } -> Option A

4. Quick Check:

   Proper if-else chain covers all cases = B [OK]

Hint: Use if-else if-else chain for multiple conditions [OK]

Common Mistakes:

• Using separate ifs causing multiple prints
• Wrong order of conditions
• Incorrect else condition logic