L4 Flashcards
What is the purpose of the Label control in a Windows Forms application?
It displays static text, such as form titles or instructions.
Why can’t you directly assign a TextBox value to an integer variable?
TextBox values are strings by default, so a conversion is required.
How do you correctly convert a TextBox value to an integer?
Use int.Parse(txtAge.Text) or Convert.ToInt32(txtAge.Text).
What is the correct way to declare an integer variable in C#?
int age = 25;
How do you display an integer variable in a TextBox?
Use txtAge.Text = age.ToString();
What is the operator for modulus (remainder) in C#?
%
What does the && operator do?
It checks if multiple conditions are true.
What does the ! operator do?
It negates a Boolean value, making true false and vice versa.
How do you calculate the sum of two numbers from TextBox inputs in a Windows Forms application?
float num1 = float.Parse(txtNum1.Text);
float num2 = float.Parse(txtNum2.Text);
float sum = num1 + num2;
lblSum.Text = sum.ToString();
What relational operator checks if two values are equal?
==
What is the output of the following code?
int a = 10, b = 5;
if (a > b) {
Console.WriteLine(“a is greater than b”);
}
“a is greater than b”
What will this code output?
bool isRainy = true;
bool hasUmbrella = false;
if (isRainy && !hasUmbrella) {
Console.WriteLine(“You will get wet!”);
}
“You will get wet!”
What is implicit type conversion in C#?
Implicit conversion occurs when the compiler automatically converts one type to another, typically from a smaller data type (e.g., int) to a larger one (e.g., long).
What is explicit type casting in C#?
Explicit casting requires the developer to manually convert one type to another, often resulting in data loss if not done properly (e.g., double to int).
How do you concatenate strings in C#?
You can concatenate strings using the + operator or the String.Concat() method. For more complex scenarios, StringBuilder can be used.
What is the default value for an uninitialized int variable in C#?
The default value for an int is 0.
What is the C# ternary operator?
The ternary operator is a shorthand for an if-else statement and has the form:
condition ? value_if_true : value_if_false;
What does the null-coalescing operator ?? do in C#?
It returns the left-hand operand if it is not null; otherwise, it returns the right-hand operand. For example:
string name = input ?? “Default Name”;
How does the try-catch block work in C#?
The try block contains code that might throw an exception, and the catch block handles the exception if it occurs.
What is string interpolation in C#?
String interpolation allows embedding expressions inside string literals using $. For example:
int age = 25;
string message = $”Your age is {age}”;
