Lesson 10 - C# Syntax Basics

Tutorial Series: Free C# Fundamentals via ASP.NET Web Apps

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This lesson will cover the basic syntax, or “grammar,” of C#. Programming languages are a bit like natural languages – such as English – except you are communicating your intent to a compiler instead of a human being. The compiler is a very complex and smart interface, but it requires very strict adherence to its rules. Whereas humans can infer details communicated in a natural language - even when they are ambiguous - a compiler is also quite dumb and demands precise, explicit instructions. If you forget even a capital letter, a period, or a semi-colon, the C# compiler will complain and refuse to render the code to a format readable by the machine.

Step 1: Combining Operators/Operands for Expressions/Statements

C# is similar to a language like English in that both are composed of statements and expressions constructed from elements that are “things,” and “actions done by those things.” In English, we would call these elements nouns and verbs, respectively. However, in C# you would say these elements are operands and operators. Operands are the "nouns", what you act on in the code. They can be literal (integer, etc.) or variable names (myString):


Operators are the "verbs" that act on the operand "nouns". There are many operators in C# that we looked at, such as assignment (=), mathematical (*, /, etc.), concatenation (+), and so on:


For an exhaustive list of operators, categorized in lists describing what they do, take a look at:


As you can see, we form complete expressions by combining operands and operators in much the same way that we combine nouns and verbs to express an idea in a natural language. These programmatic expressions even use a form of punctuation, such as terminating with a semi-colon (which is similar to how a period terminates a sentence).


There is a technical difference between expressions and statements in C#. An expression is a combination of operators and operands that evaluate to a single value, such as the simple operations seen in this lesson so far (string mySimpleName = textBox.Text). Statements, on the other hand, are complete actions. This can be a block of code that executes, a complete line of code ending in a semi-colon, calling a method, etc.

For an in-depth description of expressions, visit: http://is.gd/expressions

For an in-depth description of statements, visit: http://is.gd/statement

Step 2: Understanding Code Flow of Execution

The order in which statements are executed in a program is called the flow of control/flow of execution. Up to this point, we’ve been looking at code executed line-by-line, from top to bottom, following a linear flow order. This is the typical order in which the code will execute when compiling. Soon, we're going to learn about statements that can change the flow of execution based on different conditions being met, including:

  • If statements.

  • Switch statements.

  • Looping statements.

Step 3: Understanding Code Style

Another important aspect of syntax in C# is code style. This is one case where programming is not as strict as a written, natural language. If you submitted an English paper that had a sentence looked like this:


You would get a failing grade simply because it doesn’t follow the basic rules of English formatting which economizes whitespace (Empty space between your words). However, in a programming language like C#, these two different ways of writing a statement are treated identically by the compiler, as it just ignores whitespace:



Note: These two expressions above are equivalent to the compiler; notice the absence of a semicolon in the second expression until the very end. This tells the compiler where a singular "thought" ends.


While code styling is a matter of taste, there are some general rules to follow that you will come to notice as we progress in these lessons. The basic rule to follow is to write code that is, above all, readable by a human being. Consistent variable naming conventions, blank lines, indentations, spaces and so on, are there to make code easer for you to read.

Step 4: Real-Time Error Detection in Visual Studio

The compiler is the ultimate arbiter of C# syntax. However, Visual Studio works on behalf of the compiler - and to your benefit - to warn you when your code will not compile (with a little red squiggly line underneath the code in question). This is the compiler’s way of saying you are using unacceptable grammar (syntax) when constructing C# expressions/statements.


In the above example, the compiler is telling you that it has no idea what to do with this code, as there is no expression that resolves to a single value. What values should it add together? What is it supposed to do with that calculation, where will the value be stored? It has to be part of a valid expression in order to make sense.

There is still a lot more to say about syntax rules, but if you keep these basic rules in mind - and see a compilation error in your code - understand that it's probably because you didn’t form the code correctly, according to C#'s “grammar” rules. Refer back to the links and content provided in this lesson to help you when writing code moving forward in this course.

Related Articles in this Tutorial:

Lesson 1 - Series Introduction

Lesson 2 - Installing Visual Studio 2015

Lesson 3 - Building Your First Web App

Lesson 4 - Understanding What You Just Did

Lesson 5 - Working with Projects in Visual Studio

Lesson 6 - Simple Web Page Formatting in Visual Studio

Challenge 1

Solution 1

Lesson 7 - Variables and Data Types

Lesson 8 - Data Type Conversion

Lesson 9 - Arithmetic Operators

Lesson 10 - C# Syntax Basics

Challenge 2 - ChallengeSimpleCalculator

Solution - ChallengeSimpleCalculator

Lesson 11 - Conditional If Statements

Lesson 12 - The Conditional Ternary Operator

Challenge 3 - ChallengeConditionalRadioButton

Solution - Challenge Conditional RadioButton

Lesson 13 - Comparison and Logical Operators

Lesson 13 Challenge - First Papa Bob's Website

Solution - Challenge First Papa Bob's Website

Lesson 14 - Working with Dates and Times

Lesson 15 - Working With Spans of Time

Lesson 16 - Working with the Calendar Server Control

Challenge 4 - Challenge Days Between Dates

Solution - Challenge Days Between Dates

Lesson 17 - Page_Load and Page.IsPostBack

Lesson 18 - Setting a Break Point and Debugging

Lesson 19 - Formatting Strings

Challenge 5 - Challenge Epic Spies Assignment

Solution - Challenge Epic Spies Assignment

Lesson 20 - Maintaining State with ViewState

Lesson 21 - Storing Values in Arrays

Lesson 22 - Understanding Multidimensional Arrays

Lesson 23 - Changing the Length of an Array

Challenge 6 - Challenge Epic Spies Asset Tracker

Solution - Challenge Epic Spies Asset Tracker

Lesson 24 - Understanding Variable Scope

Lesson 25 - Code Blocks and Nested If Statements

Lesson 26 - Looping with the For Iteration Statement

Challenge 7 - Challenge For Xmen Battle Count

Solution - Challenge For Xmen Battle Count

Lesson 27 - Looping with the while() & do...while() Iteration Statements

Lesson 28 - Creating and Calling Simple Helper Methods

Lesson 29 - Creating Methods with Input Parameters

Lesson 30 - Returning Values from Methods

Lesson 31 - Creating Overloaded Methods

Lesson 32 - Creating Optional Parameters

Lesson 33 - Creating Names Parameters

Lesson 34 - Creating Methods with Output Parameters

Challenge 8 - Challenge Postal Calculator Helper Methods

Solution - Challenge Postal Calculator Helper Methods

Mega Challenge Casino

Solution - Mega Challenge Casino

Lesson 35 - Manipulating Strings

Challenge 9 - Phun With Strings

Solution - Challenge Phun With Strings

Lesson 36 - Introduction to Classes and Objects

Challenge - Hero Monster Classes Part 1

Solution - Hero Monster Classes Part 1

Challenge - Hero Monster Classes Part 2

Solution - Challenge Hero Monster Classes Part 2

Lesson 37 - Creating Class Files Creating Cohesive Classes and Code Navigation

Lesson 38 - Understanding Object References and Object Lifetime

Lesson 39 - Understanding the .NET Framework and Compilation

Lesson 40 - Namespaces and Using Directives

Lesson 41 - Creating Class Libraries and Adding References to Assemblies

Lesson 42 - Accessibility Modifiers, Fields and Properties

Lesson 43 - Creating Constructor Methods

Lesson 44 - Naming Conventions for Identifiers

Lesson 45 - Static vs Instance Members

Challenge 10 - Challenge Simple Darts

Solution - Challenge Simple Darts

Lesson 46 - Working with the List Collection

Lesson 47 - Object Initializers

Lesson 48 - Collection Initializers

Lesson 49 - Working with the Dictionary Collection

Lesson 50 - Looping with the foreach Iteration Statement

Lesson 51 - Implicitly-Typed Variables with the var Keyword

Challenge 11 - Challenge Student Courses

Solution - Challenge Student Courses

Mega Challenge War

Solution - Mega Challenge War

Lesson 52 - Creating GUIDs

Lesson 53 - Working with Enumerations

Lesson 54 - Understanding the switch() Statement

Lesson 55 - First Pass at the Separation of Concerns Principle

Lesson 56 - Understanding Exception Handling

Lesson 57 - Understanding Global Exception Handling

Lesson 58 - Understanding Custom Exceptions

Lesson 59 - Creating a Database in Visual Studio

Lesson 60 - Creating an Entity Data Model

Lesson 61 - Displaying the DbSet Result in an ASP.NET GridView

Lesson 62 - Implementing a Button Command in a GridView

Lesson 63 - Using a Tools-Centric Approach to Building a Database Application

Lesson 64 - Using a Maintenance-Driven Approach to Building a Database Application

Lesson 65 - Creating a New Instance of an Entity and Persisting it to the Database

Lesson 66 - Package Management with NuGet

Lesson 67 - NuGet No-Commit Workflow

Lesson 68 - Introduction the Twitter Bootstrap CSS Framework

Lesson 69 - Mapping Enum Types to Entity Properties in the Framework Designer

Lesson 70 - Deploying the App to Microsoft Azure Web Services Web Apps

Papa Bob's Mega Challenge

Papa Bob's Mega Solution Part 1 - Setting up the Solution

Papa Bob's Mega Solution Part 2 - Adding an Order to the Database

Papa Bob's Mega Solution Part 3 - Passing an Order from the Presentation Layer

Papa Bob's Mega Solution Part 4 - Creating the Order Form

Papa Bob's Mega Solution Part 5 - Adding Enums

Papa Bob's Mega Solution Part 6 - Creating an Order with Validation

Papa Bob's Mega Solution Part 7 - Calculating the Order Price

Papa Bob's Mega Solution Part 8 - Displaying the Price to the User

Papa Bob's Mega Solution Part 9 - Creating the Order Management Page


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