Logical patterns (and, or, not) in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of combined logical operators

What is the output of this C# code snippet?

C Sharp (C#)

bool a = true;
bool b = false;
bool c = true;

if (a && b || c)
{
    Console.WriteLine("Yes");
}
else
{
    Console.WriteLine("No");
}

A No

B Runtime exception

C Compilation error

D Yes

💡 Hint

Remember that && has higher precedence than || in C#.

The expression a && b || c is evaluated as (a && b) || c. Since a && b is false and c is true, the overall expression is true. So, "Yes" is printed.

❓ Predict Output

intermediate

Result of negation with logical operators

What will be printed by this C# code?

C Sharp (C#)

bool x = false;
bool y = true;

if (!(x || y) && y)
{
    Console.WriteLine("True branch");
}
else
{
    Console.WriteLine("False branch");
}

A Compilation error

B No output

C False branch

D True branch

💡 Hint

Evaluate the expression inside the negation first.

The expression !(x || y) && y becomes !(false || true) && true which is !true && true → false && true → false. So the else branch runs.

🔧 Debug

advanced

Identify the logical error in condition

This code is intended to print "Access granted" only if the user is an admin and is active. What is wrong with the condition?

C Sharp (C#)

bool isAdmin = true;
bool isActive = false;

if (isAdmin || isActive)
{
    Console.WriteLine("Access granted");
}
else
{
    Console.WriteLine("Access denied");
}

A The condition uses || instead of &&, so it grants access if either is true.

B The condition should use !isAdmin && !isActive.

C The else block is missing a return statement.

D The variables are not initialized properly.

💡 Hint

Think about when access should be granted.

The condition isAdmin || isActive allows access if either is true. The requirement is both must be true, so it should be isAdmin && isActive.

📝 Syntax

advanced

Identify the syntax error in logical expression

Which option contains a syntax error in the logical expression?

A if (a && (b || !c)) { }

B if (a && b || !c { }

C if (a && b || !c) { }

D if (!(a || b) && c) { }

💡 Hint

Check for missing parentheses.

Option B is missing a closing parenthesis before the opening brace, causing a syntax error.

🚀 Application

expert

Determine the number of true conditions

Given the following code, how many times will "Condition met" be printed?

C Sharp (C#)

bool[] flags = { true, false, true, false, true };
int count = 0;

foreach (bool flag in flags)
{
    if (flag && !(!flag || false))
    {
        Console.WriteLine("Condition met");
        count++;
    }
}

Console.WriteLine(count);

A 3

B 2

C 5

D 0

💡 Hint

Simplify the condition inside the if statement.

The condition flag && !(!flag || false) simplifies to flag && flag which is just flag. So it prints once for each true in the array, which are 3 times.