Introduction to C#

• With a GIS focus• With Python examples to help with transition• Provide a C# foundation for ArcGIS

customization with ArcObjects

Why customize ArcGIS ? Workflow.

ArcGIS application like ArcMap does not do EXACTLY what you want to do “out-of-the-box”.ArcObjects provides the programming framework customize ArGIS applications to do exactly what you want.

Extending ArcGISAdd-ins, C#, & ArcObjects

• Adding toolbars, buttons, tools, etc.• ArcGIS 10.1+ provides tools for making Python

Add-ins ArcGIS 10.0 did not (Free webinar)

• ArcObjects SDK for the Microsoft .NET Framework provides access to more than Python

Customization exampleCapture point features at midpoint of drawn line automatically calculatingand storing line orientation and providing easy tools for selecting type andadding dip angle.

ESRI Customization Examples

• 200+ ESRI examples in Samples folder i.e. C:\Program Files\ArcGIS\DeveloperKit10.2\Samples\ArcObjectsNet

From Python to C#

• IDE Solutions, Projects• Runtime environment• Code containers• Core language and framework• Types• Variables, operators, expressions, statements• Functions• Scope• Booleans• Flow control – branching and looping• Standard modules and libraries

IDE ProjectsPyScripter psproj• One or more related files

referenced by psproj file

Visual Studio sln and csproj• Solution (sln) can contain

one or more Projects (csproj) and other files

• Project contains one or more related files

Project is optional Solution/Project(s) not optional

Visual Studio IDE

Creating .NET Solution and Projectswith Visual Studio 2010

Projects …

… because any application worth building usually has more than one .cs file and other files (e.g. images, cursors, etc.)

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Solutions …… because Projects must be part of a Solution

Projects (.csproj)*

Visual Studio Solution (.sln)

Folder structure for application development

Download …

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Creating a src folder

- Move files up one level into src - Delete solution folder

- Create a New Project … Blank Solution, in src- Save - Exit Visual Studio

Solutions can include code from other CLS languages (e.g. VB.NET)

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Adding a Project to a Solution

Project templates

Most common Project templates

EXE

EXE

DLL ESRI Add-ins and Extensionsare compiled into DLL’s

Sln and Project code

StartUp Project• StartUp Project is the first project to run when the application is run

• Class Library Projects cannot be set as the StartUp Project

Runtime requirements

Python• PY file run from command

line or double click• Can be run interactively

>>> x = 1• Requires Python interpreter

(Python.exe) to run• Requires appropriate

version of Python.exe

C#• EXE run from command line

or double click• Cannot be run interactively

No >>> here.• Compiled assembly (EXE)

can be run directly• Requires .NET Framework

that can support assembly

Runtime – from code to CPU

Python• Python file run at command

line or double-clicked• Interpreted by Python.exe

into byte code• Byte code transformed into

machine language by Python runtime

• CPU runs machine language program

C#• Code files in Visual Studio

Solution/Project(s) compiled to Common Intermediate Language (CIL) Assembly (EXE)

• EXE run from command line or double-clicked

• Common Language Runtime (CLR) transforms CIL into machine language

• CLR and CPU run program

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.NET Framework OverviewCLS (Common Language Specification)

C#, VB.NET, Managed C++, J#

Framework Class Libraries

CLR (Common Language Runtime)

Windows OSWin32, IIS, MSMQ

Compilers

CIL (Common Intermediate Language)

UIWeb FormWinForm

WPF

ServicesWCF

WorkFlow

Data AccessADO.NET

Entity FramworkLINQ to SQL

Framework Base Classes & CTS (Common Type System)IO, Collections, Security, Threading, etc.

CLS specifes rules .NETlanguages must follow to create.NET code that will reference the.NET Framework Class Libraries(.NET DLL Assemblies) and.NET CTS.

.NET compilers will compile

.NET code into CIL stored in

.NET assemblies (EXE or DLL)

.NET CLR will perform JIT (Just-In-Time compilation) tonative machine code and ensure that the .NET assembly runs properly and securely.

Statements

• Code is interpreted or compiled one statement at a time

• A statement can be composed of one or more expressions

• Expressions are composed of one or more of the following: variables, operators, literals, function calls, and types

Statements

Python• No end of statement marker• Indentation is critical

msg = “Multi-line statement \ needs line continuation char”

C#• ; marks end of statement• Indentation is cosmetic

msg = “Multi-line statement does not need continuation char”;

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1

Statement context

PythonStatements can be run outside of functions

C#Statements cannot be run outside of functions Solution

Project Namespace Class Method

Statement

4 keywords4 names1 literal

1 keyword1 literal

Keywords

Python• ~30

C#• ~80

Types

Python• str

• int

• float

• bool (True or False)

C#• string, char

• sbyte, byte, short, ushort, int, uint, long, ulong

• float, double, decimal

• bool (true or false)

C# Types – Value types

true, false

0 – 255

‘a’, ‘b’, ‘c’, ‘\t’, etc.

28-29 significant digits, ± 7.9 x 1028

15-16 significant digits, ± 5.0 x 10324 to ±1.7 x 10308

List of constants of same type - byte, sbyte, short, ushort, int, uint, long, or ulong

7 significant digits, ±3.4 x 1038

-2,147,483,648 to 2,147,483,647

–9,223,372,036,854,775,808 to 9,223,372,036,854,775,807

-128 to 127

-32,768 to 32,767

Group of related value types

0 to 4,294,967,295

0 to 18,446,744,073,709,551,615

0 to 65,535

C# Types – Reference types

Value types require a static amount of memory (e.g. byte requires 1 byte, int uses 4 bytes, etc.) and directly contain their data.

Reference types require dynamic amounts of memory (e.g. “Bob” and “Bobby”).

Stack memoryStores values of value types and memory location of reference types in Heap Memory

Heap memoryStores reference types

Most commonly used types

string

int

double

bool

char

Classes

PythonSyntax:class name([baseClass]): [properties (data)] [methods]

C#Syntax:[scope][static] class name : baseClass { [properties] [methods] [events] etc.}

Variables

Python• Variable is case-sensitive

name associated with a value of any type

• Type defined after assignment

C#• Variable is case-sensitive

name associated with a value of a specific type

• Type defined in variable declaration statement

Variable declaration/initialization

• <type> <variableName> {= initialValue};

int x; // Declare variablex = 3; // Initialize variable

int x = 3; // Declare and initialize

int x, y, z; // Not recommended // Declare on separate lines

Rules for variable namingSame for Python and C#

Variable name syntax:– _ or letter + any number of letters, digits, or _– i.e. cannot begin with a number

Use names that describe the data they are associated with – e.g. “recordCount” is better than “n”

Use lowercase letter for first character, upper case letter for other words in name. This is called camelCase.

Cannot be a keyword of the language

Operators

Python• +, -, *, /, % same as C#• 2**3 is 23

C#• +, -, *, /, % same as Python• Math.Pow(2,3)

Output:00.50.5

C# Operators and Expressions<variable> = <operand> <operator> <operand><variable> <operator> <operand><variable> <operator>

// x = x + 1, z = x + 1// x = x + 1, z = x// x = x - 1, z = x – 1// x = x - 1, z = x

p. 46, 47 in Watson et al.++x add before expression evaluatedx++ add after expression evaluated

Operator Precedence

Same for Python and C#Parentheses/BracketsExponentiation Muliplication – DivisionAddition - Subtraction

Output: 17

Operator polymorphism

Python+ addition+ string concatenation* multiplication* string repetition

C#+ addition+ string concatenation

Comments

Python C#// Comment out single line/* Comment out multiple lines */

comments with //

C# Comments Examples//, ///, /* */

“The best kind of comments are the ones you don't need. Allow me to clarify that point. You should first strive to make your code as simple as possible to understand without relying on comments as a crutch. Only at the point where the code cannot be made easier to understand should you begin to add comments.” From http://www.codinghorror.com/blog/archives/000749.html

Functions – Syntax for Definition

PythonSyntax:def name([params]): statements [return value]

C#Syntax:[scope][static] type name ([params]){ statements [return [value];]}

scope keywords include public, internal (default), protected, protected internal, privateIf static is included, function belongs to class instead of instance of classtype refers to type returned by functionCan be any type including user-defined types. Is “void” if it returns nothingparams include type (e.g. string param1)

Functions – Define and callSyntax:[scope][static] type name ([params]){ statements [return [value];]}

Define:

Call:

Scope

“Visibility” of variables, functions, classes, etc in a program.

Class:[scope][static] class name

Function:[scope][static] type name ([params])

Variables:[scope][static] type name [= value];

Scope

Python C#

“Visibility” of variables, functions, classes, etc in a program.

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Scope Reviewpublic

internal (default)

protected

privateEntire solution

Assembly only

Derived classes

Class only

More …

More …

More …

More …

Booleans

Python C#True value: trueFalse value: false

Boolean Operators

Pythonor, and

C#|, ||, &, &&

Comparison operators are the same for Python and C#

Flow control - Branching

Flow control - Branching

Pythonif condition: # Statements for true # conditionelif condition: # Statements for alternate # true conditionelse: # if all above conditions # are false

C#if (condition){ // Statements for true // condition}else if (condition){ // Statements for alternate // true conditionelse{ // if all above conditions // are false}

Branching with if

Branching with switch

Replacing simple if … else

• If the “if … else” is being used to simply set a boolean variable, set the variable using a boolean assignment statement

Replace this

withor

Ternary (conditional) Operator ?

• Used to set a non-bool type variable based on a condition

Replace this

withor

Syntax: variable = condition ? true_expression : false_expression

Flow control - Repetition

Previous code

Code to repeat

Is condition true?

Next code

Loop

Flow control - Repetition

Pythonfor target in list: # Statements executed for # each item in list.

# Number of iterations # controlled by number of # values in list

# target is assigned each # value in list

C#foreach (type target in list){ // Statements executed for // each item in list.}

for (type target = first_value; condition_to_continue; change_target_variable){ // Statements executed // while condition to // continue is true}

Looping with for

Looping with while

Looping with do

Interrupting loops

• continue– Continue with next

target value• break

– Exit from loop• return

– Exit from loop & containing function

Standard modules/libraries

Python• Standard modules

– sys– os– os.path– urllib– xml– shutil– glob– etc.

C#• Framework Class Libraries

(DLL) organized into Namespaces like– System– System.Collections– System.IO– System.Web– System.XML– System.Data– etc.

Using modules/librariesPython C#

C:\Program Files\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\System.Xml.dll

using keyword

System namespace is part of mscorlib (Microsoft Common Object Runtime Library)

All C# programs require a reference to mscorlib

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Class libraries, namespaces, classesClass Libraries are stored ina .NET assembly (DLL)

Namespaces are a way ofnaming a group of relatedclasses and other types

Namespaces can be nested.

Namespaceicon

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.NET Framework OverviewCLS (Common Language Specification)

C#, VB.NET, Managed C++, J#

Framework Class Libraries

CLR (Common Language Runtime)

Windows OSWin32, IIS, MSMQ

Compilers

CIL (Common Intermediate Language)

UIWeb FormWinForm

WPF

ServicesWCF

WorkFlow

Data AccessADO.NET

Entity FramworkLINQ to SQL

Framework Base Classes & CTS (Common Type System)IO, Collections, Security, Threading, etc.

CLS specifes rules .NETlanguages must follow to create.NET code that will reference the.NET Framework Class Libraries(.NET DLL Assemblies) and.NET CTS.

.NET compilers will compile

.NET code into CIL stored in

.NET assemblies (EXE or DLL)

.NET CLR will perform JIT (Just-In-Time compilation) tonative machine code and ensure that the .NET assembly runs properly and securely.

Keys to remember

F1 – Context sensitive Help (If cursor is on keyword, help on keyword provided)

F6 – Build code (compile) without runningF5 – Build code (compile) and runF11 – Step through code, into called functionsF10 – Step through code, not into called

functionsShift-F5 – Stop running code F9 – Toggle Breakpoint at current statement

Links for VS 2010 and C#

• “Quick Tour” of the VS 2010 IDE

• Beginner Developer Learning Centre

• Csharp-station.com tutorial