General

Question 1

What are the data types in C#?

Answer 1

int 32 bit
long 64 bit Note that you should end the value with an “L”
float 32 bit Note that you should end the value with an “F”
double 64 bit Note that you can end the value with a “D” (although not required)
bool 1 bit
char 16 bits surrounded by single quotes
string 16 bits per character

Question 2

What is type casting?

Answer 2

Type casting is when you assign a value of one data type to another type.

Question 3

What is implicit casting?

Answer 3

Implicit casting is converting a smaller type to a larger type size.

char>int>long>float>double

Can be done automatically.

int myInt = 9;
double myDouble = myInt;

Question 4

What is explicit casting?

Answer 4

Explicit casting is converting a larger type to a smaller size type.

double>float>long>int>char

Must be done manually.

double myDouble = 9.78;
int myInt = (int) myDouble;

Question 5

What are the methods to explicitly convert a data type?

Answer 5

Convert.ToBoolean, Convert.ToDouble, Convert.ToString, Convert.ToInt32 (int) and Convert.ToInt64 (long)

int myInt = 10;
double myDouble = 5.25;
bool myBool = true;

Console.WriteLine(Convert.ToString(myInt));
Console.WriteLine(Convert.ToDouble(myInt));
Console.WriteLine(Convert.ToInt32(myDouble));
Console.WriteLine(Convert.ToString(myBool));

Question 6

What method can find the highest value of x and y?

Answer 6

Math.Max();

Question 7

What method can find the minimum value of x and y?

Answer 7

Math.Min();

Question 8

What method can find the square root of a value?

Answer 8

Math.Sqrt();

Question 9

What method can find the absolute value of number?

Answer 9

Math.Abs();

Question 10

What method will round a number to the nearest whole number?

Answer 10

Math.Round();

Question 11

How can you find the length of a string?

Answer 11

The Length property.

.Length

Question 12

How do you convert a string to upper or lower case?

Answer 12

.ToUpper()

.ToLower()

Question 13

What is the method to concatenate two strings?

Answer 13

string.Concat()

Question 14

How do you reference a certain character in a string?

Answer 14

With the index number.

string[0]

Question 15

What method can find the index value of a certain character?

Answer 15

string.IndexOf(“x”);

Question 16

How does the Substring method work?

Answer 16

Input the starting position in the arguments and the method will return a string starting at that character.

// Full name
string name = "John Doe";

// Location of the letter D
int charPos = name.IndexOf("D");

// Get last name
string lastName = name.Substring(charPos);

Question 17

What is the escape character in C#

Answer 17

\

Question 18

How do you create a new line, tab, and backspace in text in C#?

Answer 18

\n
\t
\b

Question 19

What is the syntax for a ternary operator?

Answer 19

(condition) ? “True” : “False”;

(time < 18) ? “Good day.” : “Good evening.”;

Question 20

What is the foreach loop syntax?

Answer 20

for(type variableName in arrayName){
//code block
}

Question 21

Which character do you use to make a variable nullable?

Answer 21

’?’

Examples:
int? num1 = null;
double? num2 = new double?();
bool? boolval = new bool?();