Passing value types to methods in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of passing value type to method

What is the output of the following C# code?

C Sharp (C#)

using System;
class Program {
    static void Increment(int x) {
        x = x + 1;
    }
    static void Main() {
        int a = 5;
        Increment(a);
        Console.WriteLine(a);
    }
}

A 5

B 6

C Compilation error

D Runtime error

💡 Hint

Remember that value types are passed by value by default.

The method Increment receives a copy of the value of 'a'. Changing 'x' inside the method does not affect 'a' in Main. So the output remains 5.

❓ Predict Output

intermediate

Effect of ref keyword on value type parameter

What will be printed by this C# program?

C Sharp (C#)

using System;
class Program {
    static void Increment(ref int x) {
        x = x + 1;
    }
    static void Main() {
        int a = 5;
        Increment(ref a);
        Console.WriteLine(a);
    }
}

A 6

B 5

C Compilation error

D Runtime error

💡 Hint

The ref keyword passes the variable by reference.

Using ref passes the variable itself, so changes inside Increment affect 'a'. Thus, 'a' becomes 6.

🔧 Debug

advanced

Identify the error when passing value type without ref

What error will this code produce?

C Sharp (C#)

using System;
class Program {
    static void Increment(ref int x) {
        x = x + 1;
    }
    static void Main() {
        int a = 5;
        Increment(a);
        Console.WriteLine(a);
    }
}

A No error, output is 6

B Runtime error: NullReferenceException

C Compile-time error: argument must be passed with 'ref'

D Compile-time error: method not found

💡 Hint

Check how ref parameters must be called.

The method requires 'ref' keyword when calling. Omitting it causes a compile-time error.

❓ Predict Output

advanced

Passing struct value type to method and modifying fields

What is the output of this C# program?

C Sharp (C#)

using System;
struct Point {
    public int X;
    public int Y;
}
class Program {
    static void Move(Point p) {
        p.X += 10;
        p.Y += 10;
    }
    static void Main() {
        Point pt = new Point { X = 1, Y = 1 };
        Move(pt);
        Console.WriteLine($"{pt.X}, {pt.Y}");
    }
}

A 11, 11

B Runtime error

C Compilation error

D 1, 1

💡 Hint

Structs are value types and passed by value by default.

The method Move receives a copy of the struct. Modifying the copy does not change the original 'pt'.

❓ Predict Output

expert

Passing value type with out parameter

What will be the output of this C# program?

C Sharp (C#)

using System;
class Program {
    static void Initialize(out int x) {
        x = 10;
    }
    static void Main() {
        int a;
        Initialize(out a);
        Console.WriteLine(a);
    }
}

A Compilation error: variable 'a' used uninitialized

B 10

C 0

D Runtime error: variable 'a' used before assignment

💡 Hint

Out parameters must be assigned inside the method before use.

The out parameter 'x' is assigned 10 inside Initialize, so 'a' gets value 10.