Ref and out parameters in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to pass the variable by reference using the correct keyword.

C Sharp (C#)

int number = 5;
ModifyNumber([1] number);

void ModifyNumber(ref int num) {
    num = 10;
}

Drag options to blanks, or click blank then click option'

Aref

Bout

Cin

Dvar

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'out' instead of 'ref' when the variable is already initialized.

Forgetting to use the keyword in the method call.

The ref keyword is used to pass a variable by reference, allowing the method to modify the original variable.

2fill in blank

medium

Complete the code to correctly declare an out parameter in the method signature.

C Sharp (C#)

void GetValues(int input, [1] out int result) {
    result = input * 2;
}

Drag options to blanks, or click blank then click option'

Aout

Bref

Cin

Dvar

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ref' instead of 'out' when the variable is not initialized before the call.

Not assigning a value to the out parameter inside the method.

The out keyword declares an output parameter that the method must assign before it returns.

3fill in blank

hard

Fix the error in the method call by adding the correct keyword for the out parameter.

C Sharp (C#)

int output;
CalculateSum(3, 4, [1] output);

void CalculateSum(int a, int b, out int sum) {
    sum = a + b;
}

Drag options to blanks, or click blank then click option'

Aref

Bin

Cout

Dvar

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the keyword in the method call.

Using 'ref' instead of 'out' in the call.

The out keyword must be used in both the method signature and the call when passing an out parameter.

4fill in blank

hard

Fill both blanks to correctly declare and call a method using ref parameters.

C Sharp (C#)

void Swap([1] int a, [2] int b) {
    int temp = a;
    a = b;
    b = temp;
}

int x = 1, y = 2;
Swap([1] x, [2] y);

Drag options to blanks, or click blank then click option'

Aref

Bout

Cin

Dvar

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'out' instead of 'ref' when variables are already initialized.

Forgetting to use the keyword in the method call.

The ref keyword must be used in both the method parameters and the call to pass variables by reference.

5fill in blank

hard

Fill all three blanks to create a method that uses an out parameter and call it correctly.

C Sharp (C#)

bool TryParseInt(string input, [1] out int number) {
    return int.TryParse(input, out [2] number);
}

string text = "123";
if (TryParseInt(text, [3] number)) {
    Console.WriteLine(number);
}

Drag options to blanks, or click blank then click option'

Aref

Bout

Cnumber

Dvar

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ref' instead of 'out' in any of the places.

Using a different variable name in the call to int.TryParse.

The method declares an out parameter, and the call to int.TryParse also uses out with the variable number. The call to TryParseInt uses out as well.