Getting Started with C#

 Name: Ahmed Galib Reza   Lab: Ubiquitous Computing Lab  Nationality: Bangladeshi  Education: ◦ B. IT (Hons.) Information System Engineering, Multimedia University, Malaysia. ◦ Master of Computer Engineering, Major in Ubiquitous IT, Dongseo University, South Korea.

 Introduction  Understand the basic structure of a C# program.  Obtain a basic familiarization of what a "Namespace" is.  Obtain a basic understanding of what a Class is.  Learn what a Main method does.  Learn about console input/output (I/O)  Variables and C# Data types  C# Operators

 C# (C Sharp), a successor to C++, has been released in conjunction with the.NET framework.  C# design goals: ◦ Be comfortable for C++ programmer ◦ Fit cleanly into the.NET Common Language Runtime (CLR) ◦ Simplify the C++ model ◦ Provide the right amount of flexibility ◦ Support component-centric development

using System; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { Console.WriteLine("Hello World!!"); } Uses the namespace System Entry point must be called Main Output goes to the console File name and class name need not to be identical C# is case sensitive, therefore args and Args are different identifiers Uses the namespace System Entry point must be called Main Output goes to the console File name and class name need not to be identical C# is case sensitive, therefore args and Args are different identifiers Namespace Declaration is Optional

namespace ConsoleApplication1 { class Program { static void Main(string[] args) { System.Console.WriteLine("Hello World!!"); } must use qualified name

 Replace Console.WriteLine() statement of HelloWorld Program by Console.Write() statement.  What is your output?

 Console.Write() ◦ Write the specific string to the standard output stream.  Console.WriteLine() ◦ Write the specific string, follow by current string terminator to the standard output stream.

using System; class Exercise { static void Main() { Console.WriteLine("One!!!"); Console.WriteLine("Two!!!"); Console.WriteLine("Three!!!"); }

What is your Output? Any changes? using System; class Exercise { static void Main() { Console.Write ("One!!!"); Console.Write ("Two!!!"); Console.Write ("Three!!!"); }

 Often we use special identifiers called keywords that already have a predefined meaning in the language ◦ Example: class  A keyword cannot be used in any other way

All C# keywords are Lowercase

 A variable is a typed name for a location in memory  A variable must be declared, specifying the variable's name and the type of information that will be held in it int numberOfStudents; … int average, max; data type variable name int total; … Which ones are valid variable names? myBigVar VAR1 99bottles namespace It’s-all-over numberOfStudents: average: max: total:

 An assignment statement changes the value of a variable  The assignment operator is the = sign total = 55; r You can only assign a value to a variable that is consistent with the variable's declared type (more later)  You can declare and assign initial value to a variable at the same time, e.g., int total = 55; r The value on the right is stored in the variable on the left  The value that was in total is overwritten int total; …

Example static void Main(string[] args) { int total; total = 15; System.Console.Write(“total = “); System.Console.WriteLine(total); total = ; System.Console.Write(“total = “); System.Console.WriteLine(total); }

 A constant is similar to a variable except that it holds one value for its entire existence  The compiler will issue an error if you try to change a constant  In C#, we use the constant modifier to declare a constant constant int numberOfStudents = 42;  Why constants? ◦ give names to otherwise unclear literal values ◦ facilitate changes to the code ◦ prevent inadvertent errors

 There are 15 data types in C#  Eight of them represent integers: ◦ byte, sbyte, short, ushort, int, uint, long,ulong  Two of them represent floating point numbers ◦ float, double  One of them represents decimals: ◦ decimal  One of them represents boolean values: ◦ bool  One of them represents characters: ◦ char  One of them represents strings: ◦ string  One of them represents objects: ◦ object

 The difference between the various numeric types is their size, and therefore the values they can store: Range , ,147,483,648 – 2,147,483,647 0 – 4,294,967,  to 9  – 1.8   1.0  ;  7.9  with significant digits  1.5  ;  3.4  with 7 significant digits  5.0  ;  1.7  with significant digits Type byte sbyte short ushort int uint long ulong decimal float double Storage 8 bits 16 bits 32 bits 64 bits 128 bits 32 bits 64 bits

int x = 1; short y = 10; float pi = 3.14f; // f denotes float float f3 = 7E-02f; // 0.07 double d1 = 7E-100; // use m to denote a decimal decimal microsoftStockPrice = 28.38m;

 A bool value represents a true or false condition  A boolean can also be used to represent any two states, such as a light bulb being on or off  The reserved words true and false are the only valid values for a boolean type bool doAgain = true;

 A char is a single character from the a character set  Character literals are represented in a program by delimiting with single quotes, e.g., 'a‘ 'X‘ '7' '$‘ ',‘ char response = ‘Y’;

Common Escape Sequences

 A string represents a sequence of characters, e.g., string message = “Hello World”;

using System; class Exercise { static void Main() { int CoordX; int CoordY; CoordX = 12; CoordY = -8; Console.Write("Cartesian Coordinate System: "); Console.Write("P("); Console.Write(CoordX); Console.Write(", "); Console.Write(CoordY); Console.WriteLine(")\n"); }

using System; class Exercise { static void Main() { uint DayOfBirth; uint MonthOfBirth; uint YearOfBirth; DayOfBirth = 8; MonthOfBirth = 11; YearOfBirth = 1996; Console.WriteLine("Red Oak High School"); Console.Write("Student Date of Birth: "); Console.Write(MonthOfBirth); Console.Write("/"); Console.Write(DayOfBirth); Console.Write("/"); Console.Write(YearOfBirth); Console.WriteLine(); }

using System; class NumericRepresentation { static void Main() { long CountryArea; CountryArea = L; Console.Write("Country Area: "); Console.Write(CountryArea); Console.Write("km2\n"); }

using System; class NumericRepresentation { static void Main() { float Distance = F; //Distance = F; Console.Write("Distance = "); Console.Write(Distance); Console.WriteLine("km\n"); }

using System; class Exercise { static void Main() { string Team = "Real Madrid"; string Country = "Spain"; Console.WriteLine("Welcome to the World of C# Programming!"); Console.Write("Team: "); Console.WriteLine(Team); Console.Write("Country: "); Console.WriteLine(Country); Console.WriteLine(); }

 Number Number ◦ Example :  double int  intfloat  shortint  String/NumberNumber ◦ Example :  stringint  doublestring

using System; class Exercise { static void Main() { const double PI = 3.14; int integer = (int)PI; string str = Convert.ToString(PI); double doubleValue = Convert.ToDouble(str); Console.WriteLine("const PI is {0}", PI); Console.WriteLine("integer is {0}", integer); Console.WriteLine("str is {0}", str); Console.WriteLine("doubleValue is {0}", doubleValue); }

Category (by precedence) Operator(s)Associativity Primary x.y f(x) a[x] x++ x-- new typeof default checked unchecked delegate left Unary+ - ! ~ ++x --x (T)xleft Multiplicative* / %left Additive+ -left Shift >left Relational = is asleft Equality== !=right Logical AND&left Logical XOR^left Logical OR|left Conditional AND&&left Conditional OR||left Null Coalescing??left Ternary?:right Assignment= *= /= %= += -= >= &= ^= |= =>right

using System; class Binary { public static void Main() { int x, y, result; float floatresult; x = 7; y = 5; result = x+y; Console.WriteLine("x+y: {0}", result); result = x-y; Console.WriteLine("x-y: {0}", result); result = x*y; Console.WriteLine("x*y: {0}", result); result = x/y; Console.WriteLine("x/y: {0}", result); floatresult = (float)x/(float)y; Console.WriteLine("x/y: {0}", floatresult); result = x%y; Console.WriteLine("x%y: {0}", result); result += x; Console.WriteLine("result+=x: {0}", result); } }

using System; class Unary { public static void Main() { int unary = 0; int preIncrement; int preDecrement; int postIncrement; int postDecrement; int positive; int negative; bool logNot; preIncrement = ++unary; Console.WriteLine("pre-Increment: {0}", preIncrement); preDecrement = --unary; Console.WriteLine("pre-Decrement: {0}", preDecrement); postDecrement = unary--; Console.WriteLine("Post-Decrement: {0}", postDecrement); postIncrement = unary++; Console.WriteLine("Post-Increment: {0}", postIncrement); Console.WriteLine("Final Value of Unary: {0}", unary); positive = -postIncrement; Console.WriteLine("Positive: {0}", positive); negative = +postIncrement; Console.WriteLine("Negative: {0}", negative); logNot = false; logNot = !logNot; Console.WriteLine("Logical Not: {0}", logNot); } }

OptionDescription Step IntoIf the current line contains a method, the execution point will traverse deeper into the method definition. Step OverIf the current line contains a method, the execution point will not move further into the method definition Step OutIf the current line is within a method definition, the execution point will move out of the current method and back to the point before calling the method We will discuss in more detail in next class.