C# Programming Language Fundamentals

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Questions and Answers

What is the primary purpose of the Main() method in a C# program?

To define classes used in the program

To manage data type conversions

To control the flow of application logic

To serve as the program's entry point (correct)

Which C# 9.0 feature simplifies the creation of simple programs?

Top-level statements (correct)

C# var keyword

Type definitions

Checked and unchecked keywords

Which keyword in C# allows for implicit typing of local variables?

implicit

dynamic

object

var (correct)

What must all program logic in C# be contained within?

Type definitions (C) Signup and view all the answers

Which data type conversion operation narrows the range of values a variable can hold?

Narrowing operation (B) Signup and view all the answers

When you create a new C# console application in Visual Studio, which template do you select?

C# console app (D) Signup and view all the answers

What is the significance of using the checked and unchecked keywords in data type conversions?

To manage overflow scenarios (C) Signup and view all the answers

Which of the following statements is true regarding C# program structure?

All logic must reside within type definitions. (C) Signup and view all the answers

What is the primary advantage of using string interpolation over traditional string formatting?

It improves the readability by allowing direct access to variables. (C) Signup and view all the answers

Which character prefix indicates that a string uses interpolation in C#?

$ (A) Signup and view all the answers

In the context of string interpolation, what must you NOT include after invoking a method on an interpolated variable?

A semicolon terminator (D) Signup and view all the answers

What can you do with the curly brackets in string interpolation that differentiates it from regular string formatting?

Directly manipulate variables by using methods. (D) Signup and view all the answers

What would happen if you tried to include multiple lines of executable code within the curly brackets in string interpolation?

It would result in a syntax error. (C) Signup and view all the answers

How is age modified in the expression within the curly brackets of string interpolation?

By using the expression {age += 1} as a valid operation. (A) Signup and view all the answers

In the `ToUpper()` example with string interpolation, how does it affect the output string?

It converts the name variable to uppercase in the final string. (D) Signup and view all the answers

What is a key distinction between the string.Format method and string interpolation?

String.Format requires you to manage index positions for variables. (A) Signup and view all the answers

What method is used to determine the length of a string in C#?

Length() (D) Signup and view all the answers

Which method converts a string to all uppercase letters?

ToUpper() (C) Signup and view all the answers

What does the Contains() method check in a string?

Whether the string includes a specific character or substring (B) Signup and view all the answers

What is the result of the Replace() method on a string?

It returns a new string with the replacements. (C) Signup and view all the answers

How can strings be concatenated in C#?

Using the + operator (D) Signup and view all the answers

Which escape character is used to insert a tab into a string?

\t (B) Signup and view all the answers

What does the double backslash (\) do in a string literal?

Inserts a single backslash (B) Signup and view all the answers

How is string interpolation implemented in C#?

Using curly-bracket syntax (A) Signup and view all the answers

Which output method is used to demonstrate escape characters?

Console.WriteLine() (B) Signup and view all the answers

What happens to a BigInteger variable after it is assigned a value?

It becomes immutable. (C) Signup and view all the answers

What does the NewLine property of the Environment type do?

Inserts a blank line based on the system OS (D) Signup and view all the answers

What is the function of the String.Concat() method in string operations?

It combines multiple strings into one. (C) Signup and view all the answers

Which method would you use to multiply two BigInteger objects and get a new object?

BigInteger.Multiply() (D) Signup and view all the answers

What feature introduced in C# 7.0 helps improve readability of large numbers?

Using underscores as digit separators (D) Signup and view all the answers

Which of the following escape characters triggers an alert sound?

\a (C) Signup and view all the answers

In the context of string manipulation, what does immutability mean?

Strings cannot change their value after creation. (D) Signup and view all the answers

Which of the following C# operators can be used directly with BigInteger data types?

+, -, * (C) Signup and view all the answers

When using string concatenation, how is it processed by the C# compiler?

It emits a call to String.Concat(). (D) Signup and view all the answers

Which of these methods can be used to check if a string contains a specific substring?

Contains() (D) Signup and view all the answers

What does the Length property of the System.String class return?

The number of characters in the string. (D) Signup and view all the answers

In C# 7.2, what new capability was added for hex values?

They can start with an underscore. (D) Signup and view all the answers

Which of the following methods would you use to remove whitespace from both ends of a string?

Trim() (C) Signup and view all the answers

How can you convert the contents of a string to uppercase in C#?

ToUpper() (A) Signup and view all the answers

Which method is used to split a string into an array of substrings in C#?

Split() (B) Signup and view all the answers

What does the Replace() method do in the context of strings?

Substitutes specified characters with new characters. (C) Signup and view all the answers

What is the purpose of the Compare() method in System.String?

To compare two strings for order (D) Signup and view all the answers

How can you format a string using numeric data in C#?

Using the Format() method (A) Signup and view all the answers

What syntax represents a binary literal in C#?

0b_0001 (A) Signup and view all the answers

Which of the following methods can be called on an integer (C# int) variable?

ToString() (A), GetHashCode() (C) Signup and view all the answers

What is the correct way to declare a variable as a float in C#?

5.3F (A), 5.3f (B) Signup and view all the answers

Which member of the System.Double type retrieves the smallest positive value that is greater than zero?

Epsilon (D) Signup and view all the answers

What would the output of 'bool.FalseString' yield in C#?

False (C) Signup and view all the answers

Which of the following cannot be a valid assignment to a C# bool variable?

0 (A), 1 (D) Signup and view all the answers

Which method would you use to check if a character is a letter in C#?

char.IsLetter() (A) Signup and view all the answers

Which signature allows the Main method to return an integer value?

static int Main(string[] args) (A) Signup and view all the answers

What feature was introduced in C# 9.0 regarding the application's entry point?

Top-level statements eliminate the need for the Main method. (D) Signup and view all the answers

What happens when you input a literal whole number without specifying a type in C#?

It defaults to int (A) Signup and view all the answers

Which of the following is true regarding the System.Char type?

Char represents a single character. (C) Signup and view all the answers

What will happen if you attempt to use a local variable before it has been initialized?

It will cause a compiler error. (A) Signup and view all the answers

In the context of a Main method, which of the following is a valid signature for an asynchronous method in C# 7.1?

static Task Main(string[] args) (A) Signup and view all the answers

How can you declare a variable to represent a decimal type in C#?

300.5M (A) Signup and view all the answers

What is the compiler behavior regarding top-level statements?

They will be compiled as local methods. (C) Signup and view all the answers

Which property provides the maximum limit for a double in C#?

MaxValue (A) Signup and view all the answers

Which of the following statements is TRUE about the Main method in C#?

Main can have an async signature. (D) Signup and view all the answers

Which method would return whether a character is whitespace in a specific string?

char.IsWhiteSpace() (C) Signup and view all the answers

What value does 'double.NaN' represent in C#?

A non-number (B) Signup and view all the answers

What typically determines the choice of how to construct a Main method?

The number of command-line parameters needed. (A) Signup and view all the answers

Which statement about local variable declaration is accurate?

Local variables must be initialized immediately. (B) Signup and view all the answers

Which of the following is a member property of System.ValueType?

ToString() (A), Equals() (B), GetHashCode() (C), GetType() (D) Signup and view all the answers

When using top-level statements, what is NOT allowed?

Including them within a namespace. (A) Signup and view all the answers

When declaring a variable as a shorthand for System.String, which C# keyword is used?

string (B) Signup and view all the answers

What needs to be included in an asynchronous Main method?

A return statement for a task object. (A) Signup and view all the answers

What does the generated IL for top-level statements indicate?

A class named Program is created by the compiler. (C) Signup and view all the answers

Which of the following is a consequence of using top-level statements in C#?

It reduces boilerplate code. (C) Signup and view all the answers

What does the access modifier default to for a Main method if none is specified?

Private (C) Signup and view all the answers

What is the main purpose of using the TryParse method?

To check if a string can be converted without throwing an exception. (D) Signup and view all the answers

Which of the following is a correct invocation of the Parse method for a char type?

char c = Char.Parse("x"); (D) Signup and view all the answers

What happens when TryParse fails to convert a string?

The variable defaults to a pre-defined first value. (D) Signup and view all the answers

Which structure is used to represent time intervals in C#?

TimeSpan (A) Signup and view all the answers

Which of the following statements about DateTime is TRUE?

DateTime can represent both date and time values. (C) Signup and view all the answers

What is the outcome of executing 'bool.Parse("Hello");'?

An exception is thrown. (B) Signup and view all the answers

Which namespace must be included to use BigInteger in C#?

System.Numerics (C) Signup and view all the answers

What command is used to create a new solution named Chapter3_AllProjects?

dotnet new sln -n Chapter3_AllProjects (D) Signup and view all the answers

What is the correct way to declare an integer variable with an initial value in C#?

int myInt = 0; (A) Signup and view all the answers

What is a defining characteristic of the BigInteger structure?

It can represent very large numerical values without limitation. (A) Signup and view all the answers

What will 'new TimeSpan(4, 30, 0)' represent?

4 hours, 30 minutes, and 0 seconds. (D) Signup and view all the answers

Which command adds the SimpleCSharpApp console application to the solution?

dotnet sln add . amespace oile (A) Signup and view all the answers

Which of the following statements correctly declares three boolean variables on a single line?

bool b1 = false, b2 = true, b3 = b1; (D) Signup and view all the answers

What result does a newly created boolean variable using the 'new' keyword yield?

false (D) Signup and view all the answers

What is the function of the out parameter in TryParse?

It assigns the parsed value if parsing is successful. (C) Signup and view all the answers

In C# prior to version 10, what was required to write 'Hello, World!' to the console?

namespace HelloWorld { class Program { static void Main() { Console.WriteLine('Hello, World!'); } } } (D) Signup and view all the answers

What is the purpose of the Console.ReadLine() method in the program?

To keep the console window open until a key is pressed (D) Signup and view all the answers

What does the default literal do in C#?

Assigns a variable the default value for its data type. (C) Signup and view all the answers

How does the DateOnly struct relate to SQL Server?

It aligns with SQL Server Date data type. (C) Signup and view all the answers

What happens if you assign a string with more than one character to Char.Parse?

It throws an exception. (A) Signup and view all the answers

How does case sensitivity affect C# identifiers?

Identifiers can be the same as long as the case is different. (C) Signup and view all the answers

In which scenario is it permissible to use the 'new' keyword in C#?

To create a variable instance with its default value. (A) Signup and view all the answers

What keyword is used to define the entry point for a C# application?

Main (A) Signup and view all the answers

What results from executing the method 'UseDatesAndTimes' without defining 'Console'?

It generates a compilation error. (D) Signup and view all the answers

Which variable declaration uses the System.Boolean type explicitly?

System.Boolean b4 = false; (B) Signup and view all the answers

Can TryParse parse multiple data types simultaneously?

No, it can only handle one data type at a time. (C) Signup and view all the answers

What is the default value of a newly created int variable using the 'new' keyword?

0 (D) Signup and view all the answers

What does the static keyword signify in the context of the Main() method?

It indicates that the method can be called without creating an instance of the class. (A) Signup and view all the answers

What is the benefit of using System.ValueType in the hierarchy for certain types?

It allows variables to be allocated on the stack. (A) Signup and view all the answers

Which is true about the default Main() method generated by the .NET console project template?

It has a void return type and receives an array of strings. (C) Signup and view all the answers

Which statement correctly describes the difference between value types and reference types?

Value types have a predictable lifetime and are allocated on the stack. (D) Signup and view all the answers

What should be done if a compiler error regarding 'undefined symbols' occurs?

Change the casing and spelling of the identifiers. (A) Signup and view all the answers

What functionality was introduced in C# 9 that simplifies the code structure for console applications?

Top-level statements (A) Signup and view all the answers

Which of the following shows the correct syntax for calling the default constructor of a double variable?

double d = new double(); (B) Signup and view all the answers

Which of the following is NOT part of a typical C# console application's Main() method signature?

public (B) Signup and view all the answers

What happens when you declare a string variable without an initial value in C#?

It is set to null. (B) Signup and view all the answers

In C# 9.0, how can you declare a variable instance without specifying its data type?

var variable = new(); (C) Signup and view all the answers

What is the output of the provided console application code?

***** My First C# App ***** (A), Hello World! (D) Signup and view all the answers

Which primitive type in C# corresponds to a single empty character by default?

char (A) Signup and view all the answers

Why can a C# application have more than one Main() method?

To allow for multiple entry points for testing purposes. (D) Signup and view all the answers

Why might a programmer choose to keep the Console.ReadLine() method in their application?

To lock the window so it doesn't close when the application executes. (D) Signup and view all the answers

What is a key characteristic of data types that do not derive from System.ValueType?

They can be garbage collected. (B) Signup and view all the answers

Study Notes