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1 What is C++ C++ is a general purpse, case-sensitive, free-frm prgramming language that supprts bject-riented, prcedural and generic prgramming. C++ is a middle-level language, as it encapsulates bth high and lw level language features. Object-Oriented Prgramming (OOPs) C++ supprts the bject-riented prgramming, the fur majr pillar f bject riented prgramming used in C++ are: 1. Inheritance 2. Plymrphism 3. Encapsulatin 4. Abstractin C++ OOPs Cncepts The majr purpse f C++ prgramming is t intrduce the cncept f bject rientatin t the C prgramming language. Object Oriented Prgramming is a paradigm that prvides many cncepts such as inheritance, data binding, plymrphism etc. The prgramming paradigm where everything is represented as an bject is knwn as truly bject-riented prgramming language. Smalltalk is cnsidered as the first truly bject-riented prgramming language. OOPs (Object Oriented Prgramming System) Object means a real wrd entity such as pen, chair, table etc. Object-Oriented Prgramming is a methdlgy r paradigm t design a prgram using classes and bjects. It simplifies the sftware develpment and maintenance by prviding sme cncepts: C++ Prgramming Language Page 1

2 Object Class Inheritance Plymrphism Abstractin Encapsulatin Object Any entity that has state and behavir is knwn as an bject. Fr example: chair, pen, table, keybard, bike etc. It can be physical and lgical. Class Cllectin f bjects is called class. It is a lgical entity. Inheritance When ne bject acquires all the prperties and behaviurs f parent bject i.e. knwn as inheritance. It prvides cde reusability. It is used t achieve runtime plymrphism. Plymrphism When ne task is perfrmed by different ways i.e. knwn as plymrphism. Fr example: t cnvince the custmer differently, t draw smething e.g. shape r rectangle etc. In C++, we use Functin verlading and Functin verriding t achieve plymrphism. Abstractin Hiding internal details and shwing functinality is knwn as abstractin. Fr example: phne call, we dn't knw the internal prcessing. In C++, we use abstract class and interface t achieve abstractin. C++ Prgramming Language Page 2

3 Encapsulatin Binding (r wrapping) cde and data tgether int a single unit is knwn as encapsulatin. Fr example: capsule, it is wrapped with different medicines. Advantage f OOPs ver Prcedure-riented prgramming language 1. OOPs makes develpment and maintenance easier where as in Prcedureriented prgramming language it is nt easy t manage if cde grws as prject size grws. 2. OOPs prvide data hiding whereas in Prcedure-riented prgramming language a glbal data can be accessed frm anywhere. 3. OOPs prvide ability t simulate real-wrld event much mre effectively. We can prvide the slutin f real wrd prblem if we are using the Object- Oriented Prgramming language. C vs C++ N. C C++ 1) C fllws the prcedural style prgramming. C++ is multi-paradigm. It supprts bth prcedural and bject riented. 2) Data is less secured in C. In C++, yu can use mdifiers fr class members t make it inaccessible fr utside users. 3) C fllws the tp-dwn apprach. 4) C des nt supprt functin verlading. C++ fllws the bttm-up apprach. C++ supprts functin verlading. 5) In C, yu can't use functins In C++, yu can use functins in C++ Prgramming Language Page 3

4 in structure. 6) C des nt supprt reference variables. 7) In C, scanf() and printf() are mainly used fr input/utput. 8) Operatr verlading is nt pssible in C. 9) C prgrams are divided int prcedures and mdules 10) C des nt prvide the feature f namespace. 11) Exceptin handling is nt easy in C. It has t perfrm using ther functins. structure. C++ supprts reference variables. C++ mainly uses stream cin and cut t perfrm input and utput peratins. Operatr verlading is pssible in C++. C++ prgrams are divided int functins and classes. C++ supprts the feature f namespace. C++ prvides exceptin handling using Try and Catch blck. C++ histry C++ prgramming language was develped in 1980 by Bjarne Strustrup at bell labratries f AT&T (American Telephne & Telegraph), lcated in U.S.A. Bjarne Strustrup is knwn as the funder f C++ language. It was develp fr adding a feature f OOP (Object Oriented Prgramming) in C withut significantly changing the C cmpnent. C++ prgramming is "relative" (called a superset) f C, it means any valid C prgram is als a valid C++ prgram. Let's see the prgramming languages that were develped befre C++ language. Language Year Develped By Algl 1960 Internatinal Grup C++ Prgramming Language Page 4

5 BCPL 1967 Martin Richard B 1970 Ken Thmpsn Traditinal C 1972 Dennis Ritchie K & R C 1978 Kernighan & Dennis Ritchie C BjarneStrustrup C++ Features C++ is bject riented prgramming language. It prvides a lt f features that are given belw. 1. Simple 2. Machine Independent r Prtable 3. Mid-level prgramming language 4. Structured prgramming language 5. Rich Library 6. Memry Management 7. Fast Speed 8. Pinters 9. Recursin 10.Extensible 11.Object Oriented 12.Cmpiler based 1) Simple C++ is a simple language in the sense that it prvides structured apprach (t break the prblem int parts), rich set f library functins, data types etc. C++ Prgramming Language Page 5

6 2) Machine Independent r Prtable Unlike assembly language, c prgrams can be executed in many machines with little bit r n change. But it is nt platfrm-independent. 3) Mid-level prgramming language C++ is als used t d lw level prgramming. It is used t develp system applicatins such as kernel, driver etc. It als supprts the feature f high level language. That is why it is knwn as mid-level language. 4) Structured prgramming language C++ is a structured prgramming language in the sense that we can break the prgram int parts using functins. S, it is easy t understand and mdify. 5) Rich Library C++ prvides a lt f inbuilt functins that makes the develpment fast. 6) Memry Management It supprts the feature f dynamic memry allcatin. In C++ language, we can free the allcated memry at any time by calling the free() functin. 7) Speed The cmpilatin and executin time f C++ language is fast. 8) Pinter C++ prvides the feature f pinters. We can directly interact with the memry by using the pinters. We can use pinters fr memry, structures, functins, array etc. 9) Recursin In C++, we can call the functin within the functin. It prvides cde reusability fr every functin. C++ Prgramming Language Page 6

7 10) Extensible C++ language is extensible because it can easily adpt new features. 11) Object Oriented C++ is bject riented prgramming language. OOPs makes develpment and maintenance easier where as in Prcedure-riented prgramming language it is nt easy t manage if cde grws as prject size grws. 12) Cmpiler based C++ is a cmpiler based prgramming language, it means withut cmpilatin n C++ prgram can be executed. First we need t cmpile ur prgram using cmpiler and then we can execute ur prgram. C++ Prgram Befre starting the abcd f C++ language, yu need t learn hw t write, cmpile and run the first C++ prgram. T write the first C++ prgram, pen the C++ cnsle and write the fllwing cde: #include <istream.h> #include<cni.h> vid main() { clrscr(); cut << "Welcme t C++ Prgramming."; getch(); } #include<istream.h> includes the standard input utput library functins. It prvides cin and cut methds fr reading frm input and writing t utput respectively. #include includes the cnsle input utput library functins. The getch() functin is defined in cni.h file. vid main() The main() functin is the entry pint f every prgram in C++ language. The vid keywrd specifies that it returns n value. C++ Prgramming Language Page 7

8 cut<< "Welcme t C++ Prgramming." is used t print the data "Welcme t C++ Prgramming." n the cnsle. getch() The getch() functin asks fr a single character. Until yu press any key, it blcks the screen. C++ Basic Input/utput C++ I/O peratin is using the stream cncept. Stream is the sequence f bytes r flw f data. It makes the perfrmance fast. If bytes flw frm main memry t device like printer, display screen, r a netwrk cnnectin, etc, this is called as utput peratin. If bytes flw frm device like printer, display screen, r a netwrk cnnectin, etc t main memry, this is called as input peratin. I/O Library Header Files Let us see the cmmn header files used in C++ prgramming are: Header File <istream> <imanip> <fstream> Functin and Descriptin It is used t define the cut, cin and cerr bjects, which crrespnd t standard utput stream, standard input stream and standard errr stream, respectively. It is used t declare services useful fr perfrming frmatted I/O, such as setprecisin and setw. It is used t declare services fr user-cntrlled file prcessing. Standard utput stream (cut) The cut is a predefined bject f stream class. It is cnnected with the standard utput device, which is usually a display screen. The cut is used in cnjunctin with C++ Prgramming Language Page 8

9 stream insertin peratr (<<) t display the utput n a cnsle Let's see the simple example f standard utput stream (cut): #include <istream> int main( ) { char ary[] = "Welcme t C++ tutrial"; cut << "Value f ary is: " << ary << endl; } Output: Value f ary is: Welcme t C++ tutrial Standard input stream (cin) The cin is a predefined bject f istream class. It is cnnected with the standard input device, which is usually a keybard. The cin is used in cnjunctin with stream extractin peratr (>>) t read the input frm a cnsle. Let's see the simple example f standard input stream (cin): 1. #include <istream> 2. int main( ) { 3. int age; 4. cut << "Enter yur age: "; 5. cin >> age; 6. cut << "Yur age is: " << age << endl; 7. } Output: Enter yur age: 22 Yur age is: 22 Standard end line (endl) The endl is a predefined bject f stream class. It is used t insert a new line characters and flushes the stream. Let's see the simple example f standard end line (endl): C++ Prgramming Language Page 9

10 #include <istream> int main( ) { cut << "C++ Tutrial"; cut << " shine skill"<<endl; cut << "End f line"<<endl; } Output: C++ Tutrial shine skill End f line C++ Variable A variable is a name f memry lcatin. It is used t stre data. Its value can be changed and it can be reused many times. It is a way t represent memry lcatin thrugh symbl s that it can be easily identified. Let's see the syntax t declare a variable: 1. type variable_list; The example f declaring variable is given belw: 1. int x; 2. flat y; 3. char z; Here, x, y, z are variables and int, flat, char are data types. We can als prvide values while declaring the variables as given belw: 1. int x=5,b=10; //declaring 2 variable f integer type 2. flat f=30.8; 3. char c='a'; Rules fr defining variables A variable can have alphabets, digits and underscre. C++ Prgramming Language Page 10

11 A variable name can start with alphabet and underscre nly. It can't start with digit. N white space is allwed within variable name. A variable name must nt be any reserved wrd r keywrd e.g. char, flat etc. Valid variable names: 1. int a; 2. int _ab; 3. int a30; Invalid variable names: 1. int 4; 2. int x y; 3. int duble; C++ Data Types A data type specifies the type f data that a variable can stre such as integer, flating, character etc. There are 4 types f data types in C++ language. Types Basic Data Type Data Types int, char, flat, duble, etc C++ Prgramming Language Page 11

12 Derived Data Type Enumeratin Data Type User Defined Data Type array, pinter, etc enum structure C++ Keywrds A keywrd is a reserved wrd. Yu cannt use it as a variable name, cnstant name etc. A list f 32 Keywrds in C++ Language which are als available in C language are given belw. aut break case char cnst cntinue default d duble else enum extern flat fr gt if int lng register return shrt signed sizef static struct switch typedef unin unsigned vid vlatile while A list f 30 Keywrds in C++ Language which are nt available in C language are given belw. asm dynamic_cast namespace reinterpret_cast bl explicit New static_cast false catch peratr Template friend private class this Inline public thrw cnst_cast delete Mutable prtected true try typeid Typename using virtual wchar_t C++ Operatrs An peratr is simply a symbl that is used t perfrm peratins. There can be many types f peratins like arithmetic, lgical, bitwise etc. C++ Prgramming Language Page 12

13 There are fllwing types f peratrs t perfrm different types f peratins in C language. Arithmetic Operatrs Relatinal Operatrs Lgical Operatrs Bitwise Operatrs Assignment Operatr Unary peratr Ternary r Cnditinal Operatr C++ if-else In C++ prgramming, if statement is used t test the cnditin. There are varius types f if statements in C++. if statement if-else statement nested if statement C++ Prgramming Language Page 13

14 if-else-if ladder C++ IF Statement The C++ if statement tests the cnditin. It is executed if cnditin is true. 1. if(cnditin){ 2. //cde t be executed 3. } C++ IF-else Statement The C++ if-else statement als tests the cnditin. It executes if blck if cnditin is true therwise else blck is executed. 1. if(cnditin){ 2. //cde if cnditin is true 3. }else{ 4. //cde if cnditin is false 5. } C++ IF-else-if ladder Statement The C++ if-else-if ladder statement executes ne cnditin frm multiple statements. 1. if(cnditin1) 2. { Statement; 3. } 4. else if(cnditin2) 5. { Statement; 6. } 7. else if(cnditin3) 8. { Statement; 9. } Else C++ Prgramming Language Page 14

15 12.{ Statement; 13.} C++ switch The C++ switch statement executes ne statement frm multiple cnditins. It is like if-else-if ladder statement in C switch(expressin){ 2. case value1: 3. //cde t be executed; 4. break; 5. case value2: 6. //cde t be executed; 7. break; default: 11. //cde t be executed if all cases are nt matched; 12. break; 13.} C++ Fr Lp The C++ fr lp is used t iterate a part f the prgram several times. If the number f iteratin is fixed, it is recmmended t use fr lp than while r dwhile lps. The C++ fr lp is same as C/C#. We can initialize variable, check cnditin and increment/decrement value. 1. fr(initializatin; cnditin; incr/decr){ 2. //cde t be executed 3. } C++ Nested Fr Lp In C++, we can use fr lp inside anther fr lp, it is knwn as nested fr lp. The inner lp is executed fully when uter lp is executed ne time. S if uter C++ Prgramming Language Page 15

16 lp and inner lp are executed 4 times, inner lp will be executed 4 times fr each uter lp i.e. ttal 16 times. C++ While lp In C++, while lp is used t iterate a part f the prgram several times. If the number f iteratin is nt fixed, it is recmmended t use while lp than fr lp. 1. while(cnditin){ 2. //cde t be executed 3. } C++ D-While Lp The C++ d-while lp is used t iterate a part f the prgram several times. If the number f iteratin is nt fixed and yu must have t execute the lp at least nce, it is recmmended t use d-while lp. The C++ d-while lp is executed at least nce because cnditin is checked after lp bdy. 1. d{ 2. //cde t be executed 3. }while(cnditin); C++ Break Statement The C++ break is used t break lp r switch statement. It breaks the current flw f the prgram at the given cnditin. In case f inner lp, it breaks nly inner lp. 1. jump-statement; 2. break; C++ Cntinue Statement The C++ cntinue statement is used t cntinue lp. It cntinues the current flw f the prgram and skips the remaining cde at specified cnditin. In case f inner lp, it cntinues nly inner lp. 1. jump-statement; 2. cntinue; C++ Prgramming Language Page 16

17 C++ Cntinue Statement Example 1. #include <istream> 2. int main() 3. { 4. fr(int i=1;i<=10;i++){ 5. if(i==5){ 6. cntinue; 7. } 8. cut<<i<<"\n"; 9. } 10.} C++ Gt Statement The C++ gt statement is als knwn as jump statement. It is used t transfer cntrl t the ther part f the prgram. It uncnditinally jumps t the specified label. It can be used t transfer cntrl frm deeply nested lp r switch case label. C++ Gt Statement Example Let's see the simple example f gt statement in C #include <istream> 2. int main() 3. { 4. ineligible: 5. cut<<"yu are nt eligible t vte!\n"; 6. cut<<"enter yur age:\n"; 7. int age; 8. cin>>age; 9. if (age < 18){ 10. gt ineligible; 11. } 12. else 13. { 14. cut<<"yu are eligible t vte!"; 15. } C++ Prgramming Language Page 17

18 16.} C++ Functins The functin in C++ language is als knwn as prcedure r subrutine in ther prgramming languages. T perfrm any task, we can create functin. A functin can be called many times. It prvides mdularity and cde reusability. Advantage f functins in C There are many advantages f functins. 1) Cde Reusability By creating functins in C++, yu can call it many times. S we dn't need t write the same cde again and again. 2) Cde ptimizatin It makes the cde ptimized, we dn't need t write much cde. Suppse, yu have t check 3 numbers (531, 883 and 781) whether it is prime number r nt. Withut using functin, yu need t write the prime number lgic 3 times. S, there is repetitin f cde. But if yu use functins, yu need t write the lgic nly nce and yu can reuse it several times. C++ Prgramming Language Page 18

19 Types f Functins There are tw types f functins in C prgramming: 1. Library Functins: are the functins which are declared in the C++ header files. 2. User-defined functins: are the functins which are created by the C++ prgrammer, s that he/she can use it many times. It reduces cmplexity f a big prgram and ptimizes the cde. Declaratin f a functin The syntax f creating functin in C++ language is given belw: 1. return_type functin_name(data_type parameter...) 2. { 3. //cde t be executed 4. } Call by value and call by reference in C++ There are tw ways t pass value r data t functin in C language: call by value and call by reference. Original value is nt mdified in call by value but it is mdified in call by reference. Call by value in C++ In call by value, riginal value is nt mdified. In call by value, value being passed t the functin is lcally stred by the functin parameter in stack memry lcatin. If yu change the value f functin parameter, it is changed fr the current functin nly. It will nt change the value f variable inside the caller methd such as main(). Let's try t understand the cncept f call by value in C++ language by the example given belw: Call by reference in C++ C++ Prgramming Language Page 19

20 In call by reference, riginal value is mdified because we pass reference (address). Here, address f the value is passed in the functin, s actual and frmal arguments share the same address space. Hence, value changed inside the functin, is reflected inside as well as utside the functin. Nte: T understand the call by reference, yu must have the basic knwledge f pinters. Let's try t understand the cncept f call by reference in C++ language by the example given belw: Difference between call by value and call by reference in C++ N. Call by value Call by reference 1 A cpy f value is passed t the functin 2 Changes made inside the functin is nt reflected n ther functins 3 Actual and frmal arguments will be created in different memry lcatin C++ Arrays An address f value is passed t the functin Changes made inside the functin is reflected utside the functin als Actual and frmal arguments will be created in same memry lcatin Like ther prgramming languages, array in C++ is a grup f similar types f elements that have cntiguus memry lcatin. In C++ std::array is a cntainer that encapsulates fixed size arrays. In C++, array index starts frm 0. We can stre nly fixed set f elements in C++ array. C++ Prgramming Language Page 20

21 Advantages f C++ Array Cde Optimizatin (less cde) Randm Access Easy t traverse data Easy t manipulate data Easy t srt data etc. Disadvantages f C++ Array Fixed size C++ Array Types There are 2 types f arrays in C++ prgramming: 1. Single Dimensinal Array 2. Multidimensinal Array C++ Single Dimensinal Array Let's see a simple example f C++ array, where we are ging t create, initialize and traverse array. C++ Multidimensinal Arrays The multidimensinal array is als knwn as rectangular arrays in C++. It can be tw dimensinal r three dimensinal. The data is stred in tabular frm (rw clumn) which is als knwn as matrix. C++ Prgramming Language Page 21

22 C++ Object and Class Since C++ is an bject-riented language, prgram is designed using bjects and classes in C++. C++ Object In C++, Object is a real wrld entity, fr example, chair, car, pen, mbile, laptp etc. In ther wrds, bject is an entity that has state and behavir. Here, state means data and behavir means functinality. Object is a runtime entity, it is created at runtime. Object is an instance f a class. All the members f the class can be accessed thrugh bject. Let's see an example t create bject f student class using s1 as the reference variable. 1. Student s1; //creating an bject f Student In this example, Student is the type and s1 is the reference variable that refers t the instance f Student class. C++ Class In C++, bject is a grup f similar bjects. It is a template frm which bjects are created. It can have fields, methds, cnstructrs etc. Let's see an example f C++ class that has three fields nly. 1. class Student 2. { 3. public: 4. int id; //field r data member 5. flat salary; //field r data member 6. String name;//field r data member 7. } ; C++ Cnstructr C++ Prgramming Language Page 22

23 In C++, cnstructr is a special methd which is invked autmatically at the time f bject creatin. It is used t initialize the data members f new bject generally. The cnstructr in C++ has the same name as class r structure. There can be tw types f cnstructrs in C++. Default cnstructr Parameterized cnstructr C++ Default Cnstructr A cnstructr which has n argument is knwn as default cnstructr. It is invked at the time f creating bject. C++ Parameterized Cnstructr A cnstructr which has parameters is called parameterized cnstructr. It is used t prvide different values t distinct bjects. C++ Destructr A destructr wrks ppsite t cnstructr; it destructs the bjects f classes. It can be defined nly nce in a class. Like cnstructrs, it is invked autmatically. A destructr is defined like cnstructr. It must have same name as class. But it is prefixed with a tilde sign (~). Nte: C++ destructr cannt have parameters. Mrever, mdifiers can't be applied n destructrs. C++ Plymrphism The term "Plymrphism" is the cmbinatin f "ply" + "mrphs" which means many frms. It is a greek wrd. In bject-riented prgramming, we use 3 main cncepts: inheritance, encapsulatin and plymrphism. There are tw types f plymrphism in C++: Cmpile time plymrphism: It is achieved by functin verlading and peratr verlading which is als knwn as static binding r early binding. C++ Prgramming Language Page 23

24 Runtime plymrphism: It is achieved by methd verriding which is als knwn as dynamic binding r late binding. C++ Runtime Plymrphism Example Let's see a simple example f runtime plymrphism in C #include <istream> 2. using namespace std; 3. class Animal { 4. public: 5. vid eat(){ 6. cut<<"eating..."; 7. } 8. }; 9. class Dg: public Animal 10.{ 11. public: 12. vid eat() 13. { 14. cut<<"eating bread..."; 15. } 16.}; 17.int main(vid) { 18. Dg d = Dg(); 19. d.eat(); 20. return 0; 21.} Output: Eating bread... C++ Overlading (Functin and Operatr) If we create tw r mre members having same name but different in number r type f parameter, it is knwn as C++ verlading. In C++, we can verlad: methds, C++ Prgramming Language Page 24

25 cnstructrs, and indexed prperties It is because these members have parameters nly. Types f verlading in C++ are: Functin verlading Operatrs verlading C++ Functin Overlading Having tw r mre functin with same name but different in parameters, is knwn as functin verlading in C++. The advantage f Functin verlading is that it increases the readability f the prgram because yu dn't need t use different names fr same actin. C++ Functin Overlading Example Let's see the simple example f functin verlading where we are changing number f arguments f add() methd. 1. #include <istream> 2. class Cal { 3. public: 4. static int add(int a,int b){ 5. return a + b; 6. } 7. static int add(int a, int b, int c) 8. { 9. return a + b + c; 10. } 11.}; 12.int main(vid) { 13. Cal C; 14. cut<<c.add(10, 20)<<endl; 15. cut<<c.add(12, 20, 23); 16. return 0; 17.} C++ Prgramming Language Page 25

26 Output: C++ Operatrs Overlading Operatr verlading is used t verlad r redefine mst f the peratrs available in C++. It is used t perfrm peratin n user define data type. The advantage f Operatrs verlading is t perfrm different peratins n the same perand. C++ Operatrs Overlading Example Let's see the simple example f peratr verlading in C++. In this example, vid peratr ++ () peratr functin is defined (inside Test class). 1. #include <istream> 2. class Test 3. { 4. private: 5. int num; 6. public: 7. Test(): num(8){} 8. vid peratr ++() 9. { 10. num = num+2; 11. } 12. vid Print() { 13. cut<<"the Cunt is: "<<num; 14. } 15.}; 16.int main() 17.{ 18. Test tt; tt; // calling f a functin "vid peratr ++()" 20. tt.print(); C++ Prgramming Language Page 26

27 21. return 0; 22.} C++ Functin Overriding 23.If derived class defines same functin as defined in its base class, it is knwn as functin verriding in C++. It is used t achieve runtime plymrphism. It enables yu t prvide specific implementatin f the functin which is already prvided by its base class. C++ Inheritance In C++, inheritance is a prcess in which ne bject acquires all the prperties and behavirs f its parent bject autmatically. In such way, yu can reuse, extend r mdify the attributes and behavirs which are defined in ther class. In C++, the class which inherits the members f anther class is called derived class and the class whse members are inherited is called base class. The derived class is the specialized class fr the base class. Advantage f C++ Inheritance Cde reusability: Nw yu can reuse the members f yur parent class. S, there is n need t define the member again. S less cde is required in the class. C++ Single Level Inheritance Example: Inheriting Fields When ne class inherits anther class, it is knwn as single level inheritance. Let's see the example f single level inheritance which inherits the fields nly. C++ Multi Level Inheritance Example When ne class inherits anther class which is further inherited by anther class, it is knwn as multi level inheritance in C++. Inheritance is transitive s the last derived class acquires all the members f all its base classes. C++ Prgramming Language Page 27

28 C++ Pinters The pinter in C++ language is a variable, it is als knwn as lcatr r indicatr that pints t an address f a value. Advantage f pinter 1) Pinter reduces the cde and imprves the perfrmance, it is used t retrieving strings, trees etc. and used with arrays, structures and functins. 2) We can return multiple values frm functin using pinter. 3) It makes yu able t access any memry lcatin in the cmputer's memry. Usage f pinter There are many usage f pinters in C++ language. 1) Dynamic memry allcatin In c language, we can dynamically allcate memry using mallc() and callc() functins where pinter is used. 2) Arrays, Functins and Structures Pinters in c language are widely used in arrays, functins and structures. It reduces the cde and imprves the perfrmance. Symbls used in pinter Symbl Name Descriptin & (ampersand sign) Address peratr Determine the address f a variable. C++ Prgramming Language Page 28

29 (asterisk sign) Indirectin peratr Access the value f an address. Declaring a pinter The pinter in C++ language can be declared using (asterisk symbl). 1. int a; //pinter t int 2. char c; //pinter t char Pinter Example Let's see the simple example f using pinters printing the address and value. 1. #include <istream> 2. int main() 3. { 4. int number=30; 5. int p; 6. p=&number;//stres the address f number variable 7. cut<<"address f number variable is:"<<&number<<endl; 8. cut<<"address f p variable is:"<<p<<endl; 9. cut<<"value f p variable is:"<<*p<<endl; 10. return 0; 11.} Pinter Prgram t swap 2 numbers withut using 3rd variable 1. #include <istream> 2. int main() 3. { 4. int a=20,b=10, p1=&a, p2=&b; 5. cut<<"befre swap: p1="<< p1<<" p2="<< p2<<endl; 6. p1= p1+ p2; 7. p2= p1- p2; 8. p1= p1- p2; 9. cut<<"after swap: p1="<< p1<<" p2="<< p2<<endl; 10. return 0; C++ Prgramming Language Page 29

30 11.} C++ this Pinter In C++ prgramming, this is a keywrd that refers t the current instance f the class. There can be 3 main usage f this keywrd in C++. It can be used t pass current bject as a parameter t anther methd. It can be used t refer current class instance variable. It can be used t declare indexers. C++ this Pinter Example Let's see the example f this keywrd in C++ that refers t the fields f current class. 1. #include <istream> 2. class Emplyee { 3. public: 4. int id; //data member (als instance variable) 5. string name; //data member(als instance variable) 6. flat salary; 7. Emplyee(int id, string name, flat salary) 8. { 9. this->id = id; 10. this->name = name; 11. this->salary = salary; 12. } 13. vid display() 14. { 15. cut<<id<<" "<<name<<" "<<salary<<endl; 16. } 17.}; 18.int main(vid) { 19. Emplyee e1 =Emplyee(101, "Sn", ); //creating an bject f Emplye e 20. Emplyee e2=emplyee(102, "Nakul", 59000); //creating an bject f Emplyee C++ Prgramming Language Page 30

31 21. e1.display(); 22. e2.display(); 23. return 0; 24.} C++ static In C++, static is a keywrd r mdifier that belngs t the type nt instance. S instance is nt required t access the static members. In C++, static can be field, methd, cnstructr, class, prperties, peratr and event. Advantage f C++ static keywrd Memry efficient: Nw we dn't need t create instance fr accessing the static members, s it saves memry. Mrever, it belngs t the type, s it will nt get memry each time when instance is created. C++ Static Field A field which is declared as static is called static field. Unlike instance field which gets memry each time whenever yu create bject, there is nly ne cpy f static field created in the memry. It is shared t all the bjects. It is used t refer the cmmn prperty f all bjects such as rateofinterest in case f Accunt, cmpanyname in case f Emplyee etc. C++ static field example Let's see the simple example f static field in C #include <istream> 2. class Accunt { 3. public: 4. int accn; //data member (als instance variable) 5. string name; //data member(als instance variable) 6. static flat rateofinterest; 7. Accunt(int accn, string name) 8. { 9. this->accn = accn; C++ Prgramming Language Page 31

32 10. this->name = name; 11. } 12. vid display() 13. { 14. cut<<accn<< "<<name<< " "<<rateofinterest<<endl; 15. } 16.}; 17.flat Accunt::rateOfInterest=6.5; 18.int main(vid) { 19. Accunt a1 =Accunt(201, "Sanjay"); //creating an bject f Emplyee 20. Accunt a2=accunt(202, "Nakul"); //creating an bject f Emplyee 21. a1.display(); 22. a2.display(); 23. return 0; 24.} C++ friend functin If a functin is defined as a friend functin in C++ then the prtected and private data f a class can be accessed using the functin. By using the keywrd friend cmpiler knws the given functin is a friend functin. Fr accessing the data, the declaratin f a friend functin shuld be dne inside the bdy f a class starting with the keywrd friend. Declaratin f friend functin in C++ 1. class class_name 2. { 3. friend data_type functin_name(argument/s); 4. }; C++ friend functin Example C++ Prgramming Language Page 32

33 Let's see the simple example f C++ friend functin used t print the length f a bx. 1. #include <istream> 2. class Bx 3. { 4. private: 5. int length; 6. public: 7. Bx(): length(0) { } 8. friend int printlength(bx); //friend functin 9. }; 10.int printlength(bx b) 11.{ 12. b.length += 10; 13. return b.length; 14.} 15.int main() 16.{ 17. Bx b; 18. cut<<"length f bx: "<< printlength(b)<<endl; 19. return 0; 20.} C++ virtual functin C++ virtual functin is a member functin in base class that yu redefine in a derived class. It is declare using the virtual keywrd. It is used t tell the cmpiler t perfrm dynamic linkage r late binding n the functin. C++ virtual functin Example Let's see the simple example f C++ virtual functin used t invked the derived class in a prgram. 1. #include <istream> 2. class A 3. { 4. public: C++ Prgramming Language Page 33

34 5. virtual vid display() 6. { 7. cut << "Base class is invked"<<endl; 8. } 9. }; 10.class B:public A 11.{ 12. public: 13. vid display() 14. { 15. cut << "Derived Class is invked"<<endl; 16. } 17.}; 18.int main() 19.{ 20. A* a; //pinter f base class 21. B b; //bject f derived class 22. a = &b; 23. a->display(); //Late Binding ccurs 24.} Output: Derived Class is invked Interfaces in C++ (Abstract Classes) Abstract classes are the way t achieve abstractin in C++. Abstractin in C++ is the prcess t hide the internal details and shwing functinality nly. Abstractin can be achieved by tw ways: 1. Abstract class 2. Interface Abstract class and interface bth can have abstract methds which are necessary fr abstractin. C++ Abstract class C++ Prgramming Language Page 34

35 In C++ class is made abstract by declaring at least ne f its functins as <>strng>pure virtual functin. A pure virtual functin is specified by placing "= 0" in its declaratin. Its implementatin must be prvided by derived classes. Let's see an example f abstract class in C++ which has ne abstract methd draw(). Its implementatin is prvided by derived classes: Rectangle and Circle. Bth classes have different implementatin. 1. #include <istream> 2. class Shape 3. { 4. public: 5. virtual vid draw()=0; 6. }; 7. class Rectangle : Shape 8. { 9. public: 10. vid draw() 11. { 12. cut < <"drawing rectangle..." < <endl; 13. } 14.}; 15.class Circle : Shape 16.{ 17. public: 18. vid draw() 19. { 20. cut <<"drawing circle..." < <endl; 21. } 22.}; 23.int main( ) { 24. Rectangle rec; 25. Circle cir; 26. rec.draw(); 27. cir.draw(); 28. return 0; 29.} Output: drawing rectangle... drawing circle... C++ Prgramming Language Page 35

36 Data Abstractin in C++ In C++ prgram if we implement class with private and public members then it is an example f data abstractin. Let's see the simple example f data abstractin. 1. #include <istream> 2. class Sum 3. { 4. private: int x, y, z; 5. public: 6. vid add() 7. { 8. cut<<"enter tw numbers: "; 9. cin>>x>>y; 10.z= x+y; 11.cut<<"Sum f tw number is: "<<z<<endl; 12.} 13.}; 14.int main() 15.{ 16.Sum sm; 17.sm.add(); 18.return 0; 19.} Output: Enter tw numbers: 3 6 Sum f tw number is: 9 C++ Files and Streams C++ Prgramming Language Page 36

37 In C++ prgramming we are using the istream standard library, it prvides cin and cut methds fr reading frm input and writing t utput respectively. T read and write frm a file we are using the standard C++ library called fstream. Let us see the data types define in fstream library is: Data Type fstream ifstream fstream Descriptin It is used t create files, write infrmatin t files, and read infrmatin frm files. It is used t read infrmatin frm files. It is used t create files and write infrmatin t the files. C++ FileStream example: writing t a file Let's see the simple example f writing t a text file testut.txt using C++ FileStream prgramming. 1. #include <istream> 2. #include <fstream> 3. int main () { 4. fstream filestream("testut.txt"); 5. if (filestream.is_pen()) 6. { 7. filestream << "Welcme t Shine Skill Technlgy.\n"; 8. filestream << "C++ Tutrial.\n"; 9. filestream.clse(); 10. } 11. else cut <<"File pening is fail."; 12. return 0; 13.} C++ FileStream example: reading frm a file C++ Prgramming Language Page 37

38 Let's see the simple example f reading frm a text file testut.txt using C++ FileStream prgramming. 1. #include <istream> 2. #include <fstream> 3. int main () { 4. string srg; 5. ifstream filestream("testut.txt"); 6. if (filestream.is_pen()) 7. { 8. while ( getline (filestream,srg) ) 9. { 10. cut << srg <<endl; 11. } 12. filestream.clse(); 13. } 14. else { 15. cut << "File pening is fail."<<endl; 16. } 17. return 0; 18.} 19.Nte: Befre running the cde a text file named as "testut.txt" is need t be created and the cntent f a text file is given belw: Welcme t Shine Skill Technlgy. C++ Tutrial. Output: Welcme t Shine Skill Technlgy. C++ Tutrial Nte: Befre running the cde a text file named as "testut.txt" is need t be created and the cntent f a text file is given belw: Welcme t Shine Skill Technlgy. C++ Tutrial. Output: C++ Prgramming Language Page 38

39 Welcme t Shine Skill Technlgy. C++ Tutrial C++ Prgramming Language Page 39