Terminology
- REPL stands for Read-Evaluate-Print-Loop. A REPL is a command line tool that allows users to enter lines of code and see the result in the terminal when executed.
Overview
- You may launch your REPL at any time with the command
$ dotnet script
. - Commands meant to run in the REPL are preceded with a
>
in our curriculum. Commands meant to run in the standard command line are still preceded with$
. - Once open, you can exit the REPL with the
Ctrl + C
command.
Strings and Concatenation Terminology
- String: A sequence of characters between two quotation marks which is generally used for text content.
-
Concatenate: The act of making a new string out of multiple smaller strings, usually with a
+
operator, like this:"Hello" + " " + "World"
, which creates the string"Hello World"
.
Examples
Here's an example of concatenating multiple strings together in the C# REPL:
> "Programming" + " " + "is" + " " + "awesome!"
"Programming is awesome!"
Tips
- In C#, all lines of code must end with a semi-colon (
;
). There are a few exceptions we'll learn later, but don't worry about this for now. - We can open the REPL with the
$ dotnet script
command in the Terminal (for Mac) or Command Prompt (for Windows).
Integers and Arithmetic Terminology
- Integers: A type of data representing whole numbers (numbers without decimals).
-
Operators: A special character (or characters) that indicates an action to be performed.
+
,,
,/
, and%
are all operators for mathematic functions.
Examples
Basic arithmetic works just like you'd expect:
1 + 2
4 - 3
5 * 6
9 / 2
7 + 8 * 9
(7 + 8) * 9
Overview
-
9 % 2
returns the remainder of 9 divided by 2.%
is called modulo.
Terminology
-
Assignment Operator: The
=
operator is used to set the initial value of a variable:
string exampleVariable = "hey, I'm a variable!";`
-
Lower Camel Case: C# uses lower camel case for variables just like JavaScript. Here are a few examples:
likeThis
, orevenLikeThisExampleHere
. -
Strongly-Typed Language: A language in which data types must be declared. In the following example, we state that our variable has the
string
data type:
string anotherExampleVariable = "hey, I'm a variable too!";
Overview
- C# variables must declare the type of data they contain because C# is a strongly typed language.
- To create a C# variable we need three things:
- A descriptive name.
- A data type to declare what data the variable holds such as
int
orstring
. - An initial value set with the assignment operator (
=
).
Variables and Data Types Examples
> string phrase = "Hello World";
-
string
is the data type our variable will be. -
phrase
is our descriptive name. -
"Hello World"
is the initial value.
Terminology
- Arguments: Additional information provided to a method, passed in through the parentheses following the method name.
-
Substring: A small portion of a larger string. A bit like a single word in a larger sentence. For instance,
"hello"
is a substring of the string"hello world"
. -
Pascal Case: Required naming convention for all C# methods in which all words are capitalized with no spaces. Examples include
LikeThisMethodNameHere()
orThisOtherFictionalMethodHere()
.
Methods Examples
Here are some examples of built-in methods you can call without arguments in the REPL:
> string phrase = "Programming is AWESOME";
> phrase
"Programming is AWESOME"
> phrase.ToUpper()
"PROGRAMMING IS AWESOME"
> phrase.ToLower()
"programming is awesome"
Calling built-in methods with provided arguments:
> string phraseOne = "hello world";
> string phraseTwo = "hello";
> phraseOne.Contains(phraseTwo)
true
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