Else-if ladder execution in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of else-if ladder with multiple true conditions

What will be the output of the following C# code?

C Sharp (C#)

int x = 15;
if (x > 10)
{
    Console.WriteLine("Greater than 10");
}
else if (x > 5)
{
    Console.WriteLine("Greater than 5");
}
else
{
    Console.WriteLine("5 or less");
}

A 5 or less

B Greater than 5

C Greater than 10

D No output

💡 Hint

Remember, in an else-if ladder, only the first true condition's block runs.

Since x is 15, the first condition (x > 10) is true, so it prints "Greater than 10" and skips the rest.

❓ Predict Output

intermediate

Output when no conditions in else-if ladder are true

What will be the output of this C# code snippet?

C Sharp (C#)

int y = 3;
if (y > 10)
{
    Console.WriteLine("Greater than 10");
}
else if (y > 5)
{
    Console.WriteLine("Greater than 5");
}
else
{
    Console.WriteLine("5 or less");
}

A 5 or less

B Greater than 10

C Greater than 5

D No output

💡 Hint

Check which conditions are false and what the else block does.

Since y is 3, both if and else-if conditions are false, so the else block runs printing "5 or less".

🔧 Debug

advanced

Identify the error in else-if ladder syntax

Which option contains a syntax error in the else-if ladder?

C Sharp (C#)

int z = 7;
if (z > 10)
{
    Console.WriteLine("Greater than 10");
}
else if (z > 5)
{
    Console.WriteLine("Greater than 5");
}
else
{
    Console.WriteLine("5 or less");
}

A if (z > 10) { Console.WriteLine("Greater than 10"); } else if z > 5 { Console.WriteLine("Greater than 5"); } else { Console.WriteLine("5 or less"); }

B if (z > 10) { Console.WriteLine("Greater than 10"); } else if (z > 5) { Console.WriteLine("Greater than 5"); } else { Console.WriteLine("5 or less"); }

C } ;)"ssel ro 5"(eniLetirW.elosnoC { esle } ;)"5 naht retaerG"(eniLetirW.elosnoC { )5 > z( fi esle } ;)"01 naht retaerG"(eniLetirW.elosnoC { )01 > z( fi

D if (z > 10) { Console.WriteLine("Greater than 10"); } else if (z > 5) Console.WriteLine("Greater than 5"); else { Console.WriteLine("5 or less"); }

💡 Hint

Check the syntax of the else-if condition carefully.

Option A is missing parentheses around the else-if condition, causing a syntax error.

🚀 Application

advanced

Determine the final value after else-if ladder execution

What is the value of variable result after running this code?

C Sharp (C#)

int score = 85;
string result;
if (score >= 90)
{
    result = "Excellent";
}
else if (score >= 75)
{
    result = "Good";
}
else if (score >= 60)
{
    result = "Pass";
}
else
{
    result = "Fail";
}

A "Fail"

B "Good"

C "Pass"

D "Excellent"

💡 Hint

Check which condition matches the score 85 first.

85 is not >= 90, so first if is false. 85 >= 75 is true, so result is set to "Good" and ladder stops.

🧠 Conceptual

expert

Understanding else-if ladder execution flow

Consider this else-if ladder. Which statement best describes how it executes?

C Sharp (C#)

int n = 20;
if (n < 10)
{
    Console.WriteLine("Less than 10");
}
else if (n < 20)
{
    Console.WriteLine("Less than 20");
}
else if (n == 20)
{
    Console.WriteLine("Equal to 20");
}
else
{
    Console.WriteLine("Greater than 20");
}

A All true conditions will execute their blocks in order.

B The else block executes only if all conditions are true.

C The program will print multiple lines if multiple conditions are true.

D Only the first true condition's block executes; others are skipped.

💡 Hint

Think about how else-if ladder controls flow after a true condition.

In an else-if ladder, once a true condition is found, its block runs and the rest are skipped.

Practice

1. What happens in an else-if ladder when the first condition is true?

easy

A. All conditions are checked and all true blocks run.

B. The program skips all conditions and runs the else block.

C. Only the code inside that first true condition runs.

D. The program throws an error.

Solution

1. Step 1: Understand else-if ladder behavior

   In an else-if ladder, conditions are checked one by one from top to bottom.

2. Step 2: Identify what happens when a condition is true

   When the first true condition is found, its code block runs and the rest are skipped.

3. Final Answer:

   Only the code inside that first true condition runs. -> Option C

4. Quick Check:

   First true condition runs only [OK]

Hint: First true condition runs, others skipped [OK]

Common Mistakes:

• Thinking all true conditions run
• Believing else block runs even if a condition is true
• Assuming conditions run in parallel

2. Which of the following is the correct syntax for an else-if ladder in C#?

easy

A. if condition { } else if (condition) { } else { }

B. if (condition) { } elseif (condition) { } else { }

C. if (condition) { } else if condition { } else { }

D. if (condition) { } else if (condition) { } else { }

Solution

1. Step 1: Recall correct else-if syntax in C#

   The correct keyword is else if with a space, and conditions must be in parentheses.

2. Step 2: Check each option for syntax errors

   if (condition) { } else if (condition) { } else { } uses correct if (condition), then else if (condition), and finally else. Others have syntax errors like missing parentheses or wrong keyword.

3. Final Answer:

   if (condition) { } else if (condition) { } else { } -> Option D

4. Quick Check:

   Correct else-if syntax = if (condition) { } else if (condition) { } else { } [OK]

Hint: Use 'else if' with parentheses for conditions [OK]

Common Mistakes:

• Writing 'elseif' as one word
• Omitting parentheses around conditions
• Using 'if' without parentheses

3. What is the output of this code?

int x = 15;
if (x < 10)
  Console.WriteLine("Less than 10");
else if (x < 20)
  Console.WriteLine("Less than 20");
else
  Console.WriteLine("20 or more");

medium

A. Less than 10

B. Less than 20

C. 20 or more

D. No output

Solution

1. Step 1: Evaluate first condition (x < 10)

   x is 15, which is not less than 10, so this condition is false.

2. Step 2: Evaluate second condition (x < 20)

   15 is less than 20, so this condition is true and its block runs.

3. Final Answer:

   Less than 20 -> Option B

4. Quick Check:

   15 < 20 is true, so prints 'Less than 20' [OK]

Hint: Check conditions top-down; first true runs [OK]

Common Mistakes:

• Choosing 'Less than 10' because 15 is close
• Ignoring else-if and picking else block
• Thinking no output if first false

4. Find the error in this else-if ladder code:

int score = 85;
if score >= 90
  Console.WriteLine("Grade A");
else if (score >= 80)
  Console.WriteLine("Grade B");
else
  Console.WriteLine("Grade C");

medium

A. Missing parentheses around first if condition

B. Missing semicolon after Console.WriteLine

C. Incorrect else-if keyword

D. No error

Solution

1. Step 1: Check syntax of first if statement

   The first if condition is written as if score >= 90 without parentheses, which is invalid in C#.

2. Step 2: Verify other parts

   Other conditions have correct parentheses and syntax. The semicolons are correctly placed after each Console.WriteLine statement.

3. Final Answer:

   Missing parentheses around first if condition -> Option A

4. Quick Check:

   if conditions need parentheses [OK]

Hint: Always put conditions inside parentheses [OK]

Common Mistakes:

• Omitting parentheses in if condition
• Confusing semicolon necessity after method calls
• Miswriting else-if keyword

5. You want to categorize an integer n as 'Negative', 'Zero', or 'Positive' using an else-if ladder. Which code correctly implements this?

hard

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

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

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

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

Solution

1. Step 1: Understand the categories and conditions

   We want to print 'Negative' if n < 0, 'Zero' if n == 0, and 'Positive' if n > 0.

2. Step 2: Check each option for correct condition order and logic

   if (n < 0) Console.WriteLine("Negative"); else if (n == 0) Console.WriteLine("Zero"); else Console.WriteLine("Positive"); checks n < 0 first, then n == 0, else prints 'Positive'. This covers all cases correctly.

3. Final Answer:

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

4. Quick Check:

   Correct order and conditions for categories [OK]

Hint: Check negative first, zero second, else positive [OK]

Common Mistakes:

• Checking positive before zero causing wrong output
• Using >= 0 for positive including zero
• Misordering conditions causing unreachable code