`Console.ReadLine()`

The `Console.ReadLine()`

method is used to get user input. The user input can be stored in a variable. This method can also be used to prompt the user to press `enter` on the keyboard.

Console.WriteLine("Enter your name: ");string name = Console.ReadLine();

Comments are bits of text that are not executed. These lines can be used to leave notes and increase the readability of the program.

- Single line comments are created with two forward slashes
`//`

. - Multi-line comments start with
`/*`

and end with`*/`

. They are useful for commenting out large blocks of code.

// This is a single line comment/* This is a multi-line commentand continues until the endof comment symbol is reached */

`Console.WriteLine()`

The `Console.WriteLine()`

method is used to print text to the console. It can also be used to print other data types and values stored in variables.

Console.WriteLine("Hello, world!");// Prints: Hello, world!

Arithmetic operators are used to perform basic mathematical operations on numerical values:

`+`

addition operator`-`

subtraction operator`*`

multiplication operator`/`

division operator`%`

modulo operator (returns the remainder)

int result;result = 10 + 5; // 15result = 10 - 5; // 5result = 10 * 5; // 50result = 10 / 5; // 2result = 10 % 5; // 0

String interpolation provides a more readable and convenient syntax to create formatted strings. It allows us to insert variable values and expressions in the middle of a string so that we don’t have to worry about punctuation or spaces.

int id = 100// We can use an expression with a string interpolation.string multipliedNumber = $"The multiplied ID is {id * 10}.";Console.WriteLine(multipliedNumber);// This code would output "The multiplied ID is 1000."

In C#, `Math`

provides many built-in methods for performing advanced mathematical operations. Some common methods include:

`Math.Abs()`

— calculates the absolute value of a given number`Math.Sqrt()`

— calculates the of a given number`Math.Floor()`

— rounds the given number down to the nearest integer`Math.Min()`

— takes 2 values of the same type and returns the value that is less

double x = -80;double absValue = Math.Abs(x); // 80double sqRoot = Math.Sqrt(absValue); // 8.94427190999916double floored = Math.Floor(sqRoot); // 8double smaller = Math.Min(x, floored); // -80

C# offers several shortcuts for condensing simple operations.

The addition (`+`

) and subtraction (`-`

) operators can be doubled to form the increment (`++`

) and decrement (`--`

) operators. `++`

increases a variable’s value by 1, and `--`

lowers it by 1.

`+`

, `-`

, `*`

, `/`

, and `%`

can all be combined with the equals sign (`=`

) to form compound assignment operators, such as `+=`

, the compound addition operator. These operators take a variable to the left and a value to the right, perform the specified arithmetic operation, and assign the result back into the variable.

int a = 0;a++; // a = 1a += 1; // a = 2a *= 7; // a = 14a--; // a = 13a %= 7; // a = 6