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ch2 Awp

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Pawan
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wa Chapter 2 The C# Language === — 2.1 Comments 22 Variables and Data Types 2.3 Variable Operations 2.4 Conditional Logic 25 Loops 2.6 Methods 2.7 Questions Comments can be used to document what the program does and what specific blocks or lines of code do, Since the C# compiler ignores comments, you can include them anywhere in a program without affecting your code. How to Comment? preceded by an double forward slash. “is simply ignored by the compiler. The code of line after the double forward _ Acomment is ii ee variables Declaration of variables in c# syntax “edaiztype> Example: intage; avariable age of type int (integer) is declared and it can only store integer values. ‘We can assign a value to the variable later in our program like such: int 298% age = 24: However, the variable can also be initialized to some value during declaration. For exampl int age = 24; =a] Here, a variable age of type int is declared and initialized to 24 at the same time. Since, it’s a variable, we ean change the value of variables as well. For example, intage = 24; | age= 35; Here, the value of age is changed to 35 from 24. fariables in C# must be declared before they can be used. This means, the name and type of je must be known before they can be assigned a value. This is why C# is callled a statically- Janguage Once declared, the datatype of a variable can not be changed within a scope. A scope can be lock of code where the variable is visible or available to use. If you don’t understand the ment, don’t worry we'll learn about scopes in the later chapters. -remember,we can not do the following in C#: ly typed variables: Alternatively in Ci, we can declare a variable without knowing e using var keyword. Such variables are called implicitly typed local variables. ¢ declared using var keyword must be initialized at the time of declaration. determines the type of variable from the value that is assigned to the variable, example, value is of type int. This is equivalent to: ———————————— eer ‘There are certain rules we need to follow Whily riable in C# are: nd lowercase), und > Rules for Naming Variables in Cf naming a variable. The rules for naming 2 val 1. The variable name can contain letters (upperease only. 2. The variable name must start with either letter, For —————————i‘éCsS "Rules for naming variables in Cit lerscore (_) and digits underscore or @ symbol. Name Valid subject 01 Valid. age Valid (Best practice for naming private member variables) @break Valid (Used ifname is a reserved keyword) 101 subject Invalid (Starts with digit) ‘your_name Valid Invalid (Contains whitespace) your name 3, Ciis case sensitive, It means age and Age refers to 2 di 4. Avvariable name must not be a C# keyword. For examp! name: C# Primitive Data Types 1, Boolean (bool) © Boolean data type has two possible values: true or false > Default value: false Boolean variables are generally used to check conditions such as in if statements, loops, etc. fferent variables. le, if, for, using can not be a variable Sn 2, Signed Integral These data types hold integer va a ; ‘table bi ane bt is ased fr sig. lues (both positive and negative). Out of the total available bils, 21 sbyte Size: 8 bits Range: -128 to 127 Default value: 0 For example: using System; namespace DataType class SByteExample { public static void Main(stringf| args) { sbyle level = 23; Console. WriteLine(le vel); pe: ~32,768 t0 32,767 mult value: 0 23° int Size: 32 bits Range: -231 to 231-1 Default value: 0 For example: Using System; Namespace Datatype { class IntExampie { public static void Mein(string[] args) { int score = 51092; Console.WriteLine(score); } } ‘Output; $1092 2.4 long Size: 64 bits ‘Range: —263 to 263-1 Default value: OL [Lat the end represem the value is of long type] For example: using System; namespace DataType { Class LongExample { public static void Main(string{] args) { long range = -7091821871L; Console. Write ine(range); } Output: ~7091821871 eee 3 Unsigned Integral ‘These data types only hold values equal to or types . , Breater than 0. We calls these data to tore values When We are stire, We Won"t have negative values. eee 3.1 byte Size: 8 bits Range: 0 to 255 Default valu namespace Datatype dass ByteExample { pubiic static void Main(string) args) { byte age = 62; Console. WriteLine (level); l ‘Output: 62 - 3.2 ushort Size: 16 bits Range: 0 to 65,535 Default value: 0) For example: using System: _ namespace DataType { class UShortExampie { | public static void Main(stringf] args) { ushort value = 42019; Console, WriteLine(value); 3.3 uint Size: 32 bits Range: 0 to 232-1 Default value: 0 For example: using System; namespace DataType { class UIntExample { public static void Main(stringl] ar08) { uint totalScore = 1151092; Console. WriteLine(total Score); ‘Output: 1151092 3.4 ulong Size: 64 bits Range: 0 to 264-1 Default value: 0 For example? using System; namespace DataType { class ULongExample { public static void Main(stringl] args) { ulong range = 17091821871L; Console.WriteLina(range); } Output: 17091821871 CS eT 4. fosting Point data types hold floating point vatues ie, 1236 92.17, etc. ‘41 Bloat Single-precision floating point type Sizer 32 bits Range: 1.5 * 10-45 to 3.4 x 103% Default value: 0.0F [F at the end represent the value is of float type] For example: numbers containing decimal values. For example, class FloatExample { public static void Main(stringf] args) { float number = 43.27F; Console. Writel ine{number); Output: 43.27 42 double Double-precision floating point type. Size: 64 bits Range: 5.0 « 10-324 to 1.7 x 10308 Default value; 0.0D [D at the end represent the value is of double type] For example: using System; namespace DataType { dass DoubleExample { public static void Main(stringl] args) { double value = -11092.53D; Console. WriteLine (value); } } ) Output: -11092.53 5. Character (char) D> Ttrepresents a 16°bit unicode character Size: 16 bits Default value: ‘\0" Range: U +0000 ('\u0000") to U + FFFF (uff?) For example: using System; namespace DataType { class CharExample { public static void Main(string{] args) { char cht ="u0042; char ch2 Output: B x The unicode value of *B’ is *\u0042", hence printing ch! will print ‘BY. 6. Decimal > Decimal type has more precision and a smaller range as compared to floating point (double and float). So it is appropriate for monetary calculations. Size: 128 bits Default value: 0.0M [M at the end represent the value is of decimal type] Range: (-7.9 « 1028 to 7.9 * 1028)/(100 to 28) For example: using System; namespace DataType { class DecimalExample { public static void Main(string[] args) { decimal bankBalance = §3005.25M; Console. Write ine(baikBalanca) } } ‘Ontput: $3005.25 co# Literals Let’s look at the following statement; ist number = 41; Here, 3 int is. a data type number is 2 variable and 2 Alisa literal Literals are fixed values that appear in the program, They do not require any computation. For example, 5, false, “w" are literals that appear in a program directly without any computation. 2 Boolean Literals: true and false are the available boolean literals, hey are used to initialize boolean variables. For example: bool isValid = true: bool isPresent = false: > Integer Literals: % Integer literals are used to initialize variables of integer data types ive., sbyte, short, int, long, byte, ushort, uint and ulong. + [fan ititeger literal ends with L or I, itis of type long. For best practice use L (not 1), long value! = 4200910L; long value2 = -10928190L; + fan integer literal starts with a Ox, it represents hexadecimal value. Number with no prefixes are treated as decimal value. Octal and binary representation are not allowed in Ce. int decimalValue = 25; int hexValue = Ox11c;// decimal value 284 2 Floating Point Literals: 4% Floating point literals are used to initialize variables of float and double data types. 4 Ifa floating point literal ends with a suffix f or F, itis of type float, Similarly, if it ends with d or D, it is of type double, If neither of the suffix is presemt, it is of type double by default. % These literals contains ¢ or E when expressed in scientific notation. double number = 24.67;// double by default float value = -12.29F; double scientiicNotation = 6.21e2:/ equivalent to 6:21 x 102ie., 621 > Character and String Literals: Character literals are used to initialize variables of char data types: Character literals are enclosed in single quotes, For example, “x’, ‘p’, ete. They can be represented as character, hexadecimal escape sequence, unicode representation or integral values casted to char. [ear cht = "Ry character char ch2 = "\0072'/! hexadecimal char ch3 = \u0059"y/ unicode char ch4 = (char)107¥// casted from integer String literals are the collection of character literals ® They are enclosed in double quotes. For example, “Hello”, “Easy Programming”, etc. string firstName = "Kiran*; string lastName = *Gurbani"; C# also supports escape sequence characters such as: [Character “Meaning Single quote Double quote Backslash. \n Newline \r Carriage return \t Horizontal Tab \a Alert tb Backspace that tells the compiler to perform speci fic mathematical or logical) 1d provides the following type of operators ‘An operator is a symbol manipulations. C# has rich set of built-in operators ant 1. Arithmetic Operators 2. Relational Operators 3. Logical Operators 4. Bitwise Operators 5, Assignment Operators 6. Mise Operators (eS L Arithmetic Operators ‘ollowing table shows all the arithmeti i - ete B holds 20 then” tthmietic operators supported by C#, Assume variable A holds 10 Show Examples = Adds two operands z Sulbstracts second operand from the first ea both operands A*B=200 r Divides numerator by de-numerator B/A=2 * Modulus Operator and remainder of after an integer division B%A=0 er Increment operator increases integer value by one AH = 11 = Decrement operator decreases integer value by one Av=9 9, Relational Operators Following table shows all the relational operators supported by C#. Assume variable A holds 10 and variable B holds 20, then ~ Show Examples Description e Checks if the values of two operands are equal or not, if'yesthen | (A = B) is not true condi : Checks (A!=B) is true. not equal then condition becomes true. > Checks if the value of left operand is greater than the value of right | (A > B) is not true. operand, if yes then condition becomes true. < Cheeks if the value of left operand is less than the value of right (A = B) is not true. value of right operand, if yes then condition becomes true. Checks if the value of left operand is less than or equal to the value | (A <= B) is true. of right operand, if yes then condition becomes true, 3. Logical Operators Following table shows all the logical operators supported by C#. Assume variable A holds Boolean value truc and variable B holds Boolean value false, then — condition becomes true. Called Logical OR Operator. If'any of the two operands is non zero (A |) B) is true. then condition becomes true. 1(A && B) is true, Called Logical NOT Operator. Use to reverses the logical state of its operand. If a condition is true then Logical NOT operator will make false, 4. Bitwise Operators Bitwise operator works on bits and are as follows — perform bit by bit operation. ‘The truth tables for &, |, and ‘Assume if A=60; and B = 13; then in the binary format they are as follows A=0011 1100 B=0000 1101 A&B = 0000 1100 AJB = 0011 1101 A‘B = 0011 0001 ~A=11000011 The Bitwise operators supported by C# are listed in the foll 60 and variable B holds 13, then — Show Examples = lowing table. Assume variable A holds inary AND Operator copies a bit to the result ifit (A & B) = 12, which is 0000 1100 exists in both operands. I Binary OR Operator copies a bit if it exists in (A|B)=61, which is 0011 1101 either operand, ee Binary XOR Operator copies the bit if it is set in (A* B) = 49, which is 0011 0001 ‘one operand but not both. inary Ones Complement Opera 1 has the effect of “fipping’ bite SMAY and (-A)= 61, which is 1100 0011 complement due to a signed binary number. Binary Left Shift Operator, The lei is moved left by the number of eas alte + of bits specified by A <<2= 240, which is 1111 0000 ‘There are following assignment operators supported by C# — Show Examples Simple assignment operator, Assigns values from right side operands to left side operand Add AND assignment operator, Itadds Tight operand to the left operand and assign the result to left operand the right operand, Binary Right Shift Operator. The = + The left operands = ae value is moved right by the number of bis slieaieipaiaiass specified by the right operand, 5, Assignment Operators __ Example C= A+B assigns value of A + B into C += A is equivalent toC =C + Subtract AND assignment operator, t subtracts right operand from the left operand and assign the result to left operand is equivalent to C = C - Multiply AND assignment operator, It multiplies right operand with the left operand and assign the result to left operand C *=A is equivalent toC =C* A Divide AND assignment operator, It divides left operand with the right operand and assign the result to left operand C/=A is equivalent toC=C/ A Modulus AND assignment operator, It takes modulus using two operands and assign the result to left operand = ‘Yr A is equivalent to C=C A <= Left shift AND assignment operator C <<=2 issameas C=C<<2 ae Right shift AND assignment operator C>>=2issameasC=C>>2 & Bitwise AND assignment operator C & 2issameasC=C &2 a Bitwise exclusive OR and assignment operator C*%=2 is same as C= C2 F Bitwise inclusive OR and assignment operator C{=2issameasC=C|2 6. Miscellaneous Operators There are few other important operators including sizeof, typeof and ?:supported by C#. = Description Returns the size of a data type. sizeoitint), returns 4. typeof StreamReader); Returns the type of a class. Returns the address of an variable. ‘a; returns actual address of the variable, e Pointer to a variable ‘a; creates pointer named ‘a’ to a variable. % ‘Conditional Expression If Condition is true ? Then value X: Otherwise value ¥ If (Ford is Car) // checks if Ford is an object of the Car class. ‘Determines whether an object is of a certain type. as Cast without raising an exception ifthe cast | Object obj = new SiringReader(“Hello”); fails. StringReader r= obj as StringReader; Operator Precedence in C# n expression. This affects evaluation Operator precedence determines the grouping of terms in a hers; for example, the multiplication of an expression. Certain operators have higher precedence than ot! ‘operator has higher precedence than the addition operator. For exemple x = 7 +3 * 2; here, x is assigned 13, not 20 because operalor * has higher precedence than +, so the first evaluation takes place for 3*2 and then 7 is added into it Here, operators with the highest precedence appear at the top of the table, those with the lowes, appear atthe bottom. Within an expression, higher precedence operators are evaluated first. Show Examples Left to right Unary 4-1 ~44-- (type)? & sizeof Right to teft | Multiplicative *i% Left to right | Additive #5 Left to right | Shift <<>> Left to right | Relational <>= Left to right Equality ' Left to right | | Bitwise AND. & Left to right Bitwise XOR a Left to right | Bitwise OR | Left to right Logical AND && Left to right Logical OR _| il “ [eft to right Conditional Right to left Ia tnr— com dys hm f= | Rightto lef Sto=0 ‘A-statement that can be executed : b ot atement is often a block of code ased on a condition is known as a “Conditional Statement”. The following are the 2 types; 1. Cobditional Branching 2, | Conditional Looping 4, Conditional Branching is statement allow: cl This S you to branch your code depending on whether or not a certain condition is In C# are the following 2 conditional branching statements: 1. IF statement 4, Switch statement IF Statement ‘The if statement allows you to test whether or not a specific condition is met. syntax if() ; Else if() -; Else: -; oP he pos Example Write a Program to find the greatest number using an if statement 4, using System: 2 clags ildemo af 4, public static void Main() 5 f 6 inta,b: 7. Console. WriteLine(“enter 2 no "} |. a=int Parse (Console Readline()) | 9. _ b=Int Parse(Console ReadLine()): | 10. if(a>t) 4 42, Console WrteLinet“e is greater’) 3 14, else If(a<'b) 45. { 46. Console WriteLina(’b is greather); 47. } 18. else 19. { 20. Console: WeiteLineboth ave Equals”); 2} 22, Console, ReedLine(): 123, 3 Switch Statement The switch statement compares two logical ex] ‘Syntax Swilth() { Case : Break; pressions. Default: . Break; ) ageneeace 23 %e sees one u Note: In the case of the C# Language, using a break after every case block is mandatory, even’ the default. i Le) exariple SBR Write @ Program to choose & color sing a swi tch case, ‘ing System; using System Collections. Generic; using System. Ling; using System.Text; using System. Threading Tasks: namespace ConditionalStatementDemo. { class Switchdemo { int ch; Public void getdata() { ‘Console. WriteLine(“choose the following coli); ‘ch = int Parse(Console,ReadLina()); ‘switch (ch) { case 1: Console WriteLine¢"you choose Red"); break; case 2 Console. WriteL ine(*you choose Green"); break; case 3: Console.WriteLine("you choose Pink"); break; default Console Writél ine(*you cant choose cortect eblor'); break; } public static void Main() { ‘Switchdemo obj = new Switchdemo\); obj.gatdata(); Console. ReadLine() | Conditional Loops C# provides 4 loops that allow you to execute @ bl is met; they are: > For Loop 3 While Loop: 2 Do... While Loop 2 Foreach Loop Jock of code repeatedly until a certain condition Each and every loop requires the following 3 things in common: 4. Initialization: That sets a starting point of the loop. 2. Condition: That sets an ending point of the loop. 3, Iteration: That provides each level, either in the forward or backward direction. Direction Syntax 1. For(initializar;Conition;{terator) 2 { 3. 4} Example 4. using System; 2. _ using System.Collections.Generic, 3. using System.Ling: 4, using System.Text; 5. using System. Threading.Tasks, 6. 7. 8. namespace ConditionalStatementDemo sf o class FotLoop 10 { 1. 12. Public void getdata() a its 50; 144) Console. WriteLine(iy } } public static void Main() { a ForLoop # = new Fort oop(); f.getdata(); Console. Read ine(); 7, While(Condition) mint 3, 4) Example 4, using System; 2. using System. Collections. Generic: 3, using System.Ling; 4, _using System.Text; 5, using System: Threading. Tasks; 6 7. 8 9. namespace ConditionalStatementDemo Class WhileDemo AC ib M1. int x 12. public void whiledemo() 13, { 14, while (x <= $0) rs { 16. Console. Writeline(x); Do... } ‘ public static void Main() { \Whiebemo obj = new WhileDemo( obj whiledemo(); Console.ReadLinet); . While Loop ‘Syntax 1. a 3. 4. 3 pee ‘Do { < statement > } While(Condition) i using System; using System.Collections,Generic; using System.Ling; using System.Text; using System. Threading Tasks; namespace ConditionalStatementDemo { class DoWtileDemo { int x; public void does() do { Console WriteLine(x); att; } while (x <= 50); public static void Maing) { DoWhieDeme obj = new DoWhileDemoy); ‘Gbj.does(); Console. ReadLine(); In the-case of a for and a while loop from the fist exeeution there will be condition verification. But in the case of 4 do .. while, the condition is verified only after the first execution, soa rinimam umber of executions occur. In the case of far and while the’ minimurs number of executions will be zero whereas it is | in the case of a do-while loap. Foreach Loop Itis specially designed for accessing the values of an array and collection. Syntax Foreach(type var in col/Arr) 1 24 3, statement >; 4. Amethod is a code block that contains a series of statements. A program causes the statements to be executed by calling the method and specifying any required method arguments, In C#, every executed instruction is performed in the context of a method. ‘The Main method is the entry point for every C# application and it is called by the common language runtime (CLR) when the program is started. Method Signatures Methods are declared in a class or struct by specifying the access level such as public or private, optional modifiers such as abstract or sealed, the zeturn value, the name ofthe method, and any method parameters. These parts together arc the signature of the method.] ed by commas. Empty parenthesey hree methods:! ses and are separati ___ Method parameters are enclosed in parenth indicate that the method requires no parameters: abstract class Motorcycle { This class contains I Anyone can call this public void StartEnginel) (* Method statements here ry : Il Only derived classes can call this protected void AddGas(int gallons) { * Method JI Derived classes can override the base class implementation. public vitual int Drive(int miles, int speed) { * Method statements here */ return 1; } 1 Derived classes must implement this. public abstract double GetTonSpeed(); statements here “/ } Method Access Calling a method on an object is like accessing @ field. After the object name, add a period, the name of the method, and parentheses. Arguments are listed within the parentheses, and are separéted by commas. The methods of the Motorcycle class can therefore be called as in the following example: ‘class TestMotorcycle: Motorcycle Tl { public override double GetTopSpeed() | | { return 108.4; } static void Main() | { TestMotorcycie moto = new TestMotorcycle(); moto StartEngine(); moto.AddGas(15), | moto Drive(5, 20); double speed = moto.GetTopSpeed(): Console. WriteLine("My top speed is (0)", speed); } Method Parameters vs. Arguments i ee definition specifies the names and types of any parameters that are required. When | calling code calls the method, it provides concrete values called arguments for each parameter, The | must be compatible with the 5, Signs oh a ttt eae ay) wee Meter named defined in the method. For example: ponte void Caller() { inurumA = 4; 1). Call with an int variable int product = Square(numA); int numB = 32; i Call with another int variable, int productB = Square(numB); 1) Call with arvintegor literal, int productC = Square(12); 1) Call with an expression that evaulates to int, product = Squara(producta * 3): ) int Square(int i) { / Store input argument in a local variable. int input =f retum input * input: Explain data type in C#? What is Constant? Explain type of Constants in C#? ‘What is Keyword and list some keyword in C#? ‘What are different Rules for defining variable names? Expiain syntax of conditional statements if and if-else with suitable example Explain Different types of Loops with syntax Explain For loop syntax with suitable example. Explain while loop syntax with suitable example. Explain how to declare and Access Methods in C# yes eee o oOo

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