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C# Tutorial - Variables, If/Else, While Loop and More!
Elizabeth11 (21)

Hi and welcome to this C# tutorial! Hope this helps you out!

Important notes:

  • C# uses // for single line comments.
    • Ex: //computer doesn't read this
  • C# places a semicolon ; at the end of each statement.
    • Ex: int a = 5;

Variables:

These are the main variables which will be dicussed here. There are more but here are the basics.

  • Strings:
    • They are made up of multiple characters.
    • They are surrounded by double quotes
    • Ex: string name = "Bob";
  • Integers:
    • Are integers. Are whole numbers.
    • Ex: int b = 6;
  • Doubles:
    • Have a decimal point and are more precise than integers.
    • Ex: double num = 5.01;
  • Booleans:
    • Are either true or false.
    • Ex: bool fun = true;

Converting

In the repl.it that is included with this tutorial there are some conversions.
.toString(); -> Converts to a string
Convert.toDouble(); -> Converts to a double
Convert.toInt32(); -> Converts to an int


Output and Input

  • Output:
    • Console.WriteLine(); is used to write something on a new line.
    • Console.Write(); writes something on the same line
      • Ex: Console.WriteLine("Hello World");
  • Input:
    • Console.ReadLine(); returns the input as a string.

If/Else Statements (Conditionals)

An if statement is executed when something results to true. An if statement has a condition and body. If the condition is true then the body will run.

An example of a condition is a == 5. Note that the == is used because it is comparing two things. A != is the comparison operator for not true.

Example of an if statement:

int choice = Convert.ToInt32(Console.ReadLine());

if(choice == 1) //addition
{
        double addition_output = first_num + second_num;
	Console.WriteLine("You have choosen addition!");
	Console.WriteLine("Output: " + addition_output);
}

An else statement is only executed if the rest are false. If you use 3 if statements and then an else statement then the code will try each if statement but if you use an if- else if- else setup then the code will only try 1 if statement.


While Loop

A while loop can be used to continue to do something while a condition results to true.

In the calculator program included in this tutorial there is a variable declared at the very beginning like this: bool try_again = true;. Then at the end, once the person has finised, if they input something other than yes for continuing the game the else statement body contains code which is try_again = false which terminates the while loop. Every while loop needs a terminating condition or it will become an infinite loop!

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