If a copy constructor is not defined in a class, the compiler itself defines one. If the class has pointer variables and has some dynamic memory allocations, then it is a must to have a copy constructor. Length of line : 10 Freeing memory! Freeing memory! Copy constructor allocating ptr. Friend Functions A friend function of a class is defined outside that class' scope but it has the right to access all private and protected members of the class.
Even though the prototypes for friend functions appear in the class definition, friends are not member functions. A friend can be a function, function template, or member function, or a class or class template, in which case the entire class and all of its members are friends. If a function is inline, the compiler places a copy of the code of that function at each point where the function is called at compile time.
Any change to an inline function could require all clients of the function to be recompiled because compiler would need to replace all the code once again otherwise it will continue with old functionality. To inline a function, place the keyword inline before the function name and define the function before any calls are made to the function.
The compiler can ignore the inline qualifier in case defined function is more than a line. A function definition in a class definition is an inline function definition, even without the use of the inline specifier. The this pointer is an implicit parameter to all member functions.
Therefore, inside a member function, this may be used to refer to the invoking object. Friend functions do not have a this pointer, because friends are not members of a class.
Only member functions have a this pointer. Also as with all pointers, you must initialize the pointer before using it. Constructor called. Volume of Box1: 5. When we declare a member of a class as static it means no matter how many objects of the class are created, there is only one copy of the static member. A static member is shared by all objects of the class. All static data is initialized to zero when the first object is created, if no other initialization is present.
We can't put it in the class definition but it can be initialized outside the class as done in the following example by redeclaring the static variable, using the scope resolution operator :: to identify which class it belongs to. Total objects: 2 Static Function Members By declaring a function member as static, you make it independent of any particular object of the class. A static member function can be called even if no objects of the class exist and the static functions are accessed using only the class name and the scope resolution operator A static member function can only access static data member, other static member functions and any other functions from outside the class.
Static member functions have a class scope and they do not have access to the this pointer of the class. You could use a static member function to determine whether some objects of the class have been created or not. Inheritance allows us to define a class in terms of another class, which makes it easier to create and maintain an application.
This also provides an opportunity to reuse the code functionality and fast implementation time. When creating a class, instead of writing completely new data members and member functions, the programmer can designate that the new class should inherit the members of an existing class.
This existing class is called the base class, and the new class is referred to as the derived class. The idea of inheritance implements the is a relationship. To define a derived class, we use a class derivation list to specify the base class es. A class derivation list names one or more base classes and has the form: class derived-class: access-specifier base-class Where access-specifier is one of public, protected, or private, and base-class is the name of a previously defined class.
If the access-specifier is not used, then it is private by default. Thus base-class members that should not be accessible to the member functions of derived classes should be declared private in the base class.
Type of Inheritance When deriving a class from a base class, the base class may be inherited through public, protected or private inheritance. The type of inheritance is specified by the access-specifier as explained above. We hardly use protected or private inheritance, but public inheritance is commonly used. A base class's private members are never accessible directly from a derived class, but can be accessed through calls to the public and protected members of the base class.
Where access is one of public, protected, or private and would be given for every base class and they will be separated by comma as shown above. An overloaded declaration is a declaration that is declared with the same name as a previously declared declaration in the same scope, except that both declarations have different arguments and obviously different definition implementation. When you call an overloaded function or operator, the compiler determines the most appropriate definition to use, by comparing the argument types you have used to call the function or operator with the parameter types specified in the definitions.
The process of selecting the most appropriate overloaded function or operator is called overload resolution. You cannot overload function declarations that differ only by return type. Thus, a programmer can use operators with user-defined types as well. Overloaded operators are functions with special names the keyword operator followed by the symbol for the operator being defined. Like any other function, an overloaded operator has a return type and a parameter list.
Most overloaded operators may be defined as ordinary non-member functions or as class member functions. The unary operators operate on the object for which they were called and normally, this operator appears on the left side of the object, as in! Following example explain how minus - operator can be overloaded for prefix as well as postfix usage. Similar way, you can overload operator You can overload any of these operators, which can be used to compare the objects of a class.
The stream insertion and stream extraction operators also can be overloaded to perform input and output for user-defined types like an object. Here, it is important to make operator overloading function a friend of the class because it would be called without creating an object. Following example explains how an assignment operator can be overloaded.
When you overload , you are not creating a new way to call a function. Rather, you are creating an operator function that can be passed an arbitrary number of parameters. Following example explains how a function call operator can be overloaded. Following example explains how a subscript operator [] can be overloaded. It is defined to give a class type a "pointer-like" behavior.
If used, its return type must be a pointer or an object of a class to which you can apply. Typically, polymorphism occurs when there is a hierarchy of classes and they are related by inheritance.
This is called static resolution of the function call, or static linkage - the function call is fixed before the program is executed. This is also sometimes called early binding because the area function is set during the compilation of the program.
This is how polymorphism is generally used. You have different classes with a function of the same name, and even the same parameters, but with different implementations. Virtual Function A virtual function is a function in a base class that is declared using the keyword virtual.
Defining in a base class a virtual function, with another version in a derived class, signals to the compiler that we don't want static linkage for this function. What we do want is the selection of the function to be called at any given point in the program to be based on the kind of object for which it is called. This sort of operation is referred to as dynamic linkage, or late binding.
Pure Virtual Functions It is possible that you want to include a virtual function in a base class so that it may be redefined in a derived class to suit the objects of that class, but that there is no meaningful definition you could give for the function in the base class. Data abstraction is a programming and design technique that relies on the separation of interface and implementation.
Let's take one real life example of a TV, which you can turn on and off, change the channel, adjust the volume, and add external components such as speakers, VCRs, and DVD players, BUT you do not know its internal details, that is, you do not know how it receives signals over the air or through a cable, how it translates them, and finally displays them on the screen.
Thus, we can say a television clearly separates its internal implementation from its external interface and you can play with its interfaces like the power button, channel changer, and volume control without having zero knowledge of its internals. They provide sufficient public methods to the outside world to play with the functionality of the object and to manipulate object data, i.
For example, your program can make a call to the sort function without knowing what algorithm the function actually uses to sort the given values. In fact, the underlying implementation of the sorting functionality could change between releases of the library, and as long as the interface stays the same, your function call will still work. The data-abstraction view of a type is defined by its public members.
The private sections hide the implementation from code that uses the type. There are no restrictions on how often an access label may appear. Each access label specifies the access level of the succeeding member definitions.
The specified access level remains in effect until the next access label is encountered or the closing right brace of the class body is seen. By defining data members only in the private section of the class, the class author is free to make changes in the data. If the implementation changes, only the class code needs to be examined to see what affect the change may have.
If data is public, then any function that directly access the data members of the old representation might be broken. The public members - addNum and getTotal are the interfaces to the outside world and a user needs to know them to use the class.
The private member total is something that the user doesn't need to know about, but is needed for the class to operate properly. So while designing your component, you must keep interface independent of the implementation so that if you change underlying implementation then interface would remain intact.
In this case whatever programs are using these interfaces, they would not be impacted and would just need a recompilation with the latest implementation. Encapsulation is an Object Oriented Programming concept that binds together the data and functions that manipulate the data, and that keeps both safe from outside interference and misuse.
Data encapsulation led to the important OOP concept of data hiding. Data encapsulation is a mechanism of bundling the data, and the functions that use them and data abstraction is a mechanism of exposing only the interfaces and hiding the implementation details from the user.
We already have studied that a class can contain private, protected and public members. By default, all items defined in a class are private. This means that they can be accessed only by other members of the Box class, and not by any other part of your program. This is one way encapsulation is achieved. To make parts of a class public i. Making one class a friend of another, exposes the implementation details and reduces encapsulation.
The ideal is to keep as many of the details of each class hidden from all other classes as possible. The private member total is something that is hidden from the outside world, but is needed for the class to operate properly. Designing Strategy Most of us have learnt to make class members private by default unless we really need to expose them.
That's just good encapsulation. This is applied most frequently to data members, but it applies equally to all members, including virtual functions.
A class is made abstract by declaring at least one of its functions as pure virtual function. Abstract classes cannot be used to instantiate objects and serves only as an interface. Attempting to instantiate an object of an abstract class causes a compilation error. Thus, if a subclass of an ABC needs to be instantiated, it has to implement each of the virtual functions, which means that it supports the interface declared by the ABC. Failure to override a pure virtual function in a derived class, then attempting to instantiate objects of that class, is a compilation error.
Classes that can be used to instantiate objects are called concrete classes. Designing Strategy An object-oriented system might use an abstract base class to provide a common and standardized interface appropriate for all the external applications. Then, through inheritance from that abstract base class, derived classes are formed that operate similarly. The implementations of these pure virtual functions are provided in the derived classes that correspond to the specific types of the application.
This architecture also allows new applications to be added to a system easily, even after the system has been defined. This tutorial will teach you how to read and write from a file. Opening a File A file must be opened before you can read from it or write to it. Either ofstream or fstream object may be used to open a file for writing. And ifstream object is used to open a file for reading purpose only.
Following is the standard syntax for open function, which is a member of fstream, ifstream, and ofstream objects. All output to that file to be appended to the end. You can combine two or more of these values by ORing them together. For example if you want to open a file in write mode and want to truncate it in case that already exists, following will be the syntax: ofstream outfile; outfile. But it is always a good practice that a programmer should close all the opened files before program termination.
Following is the standard syntax for close function, which is a member of fstream, ifstream, and ofstream objects. The only difference is that you use an ofstream or fstream object instead of the cout object. The only difference is that you use an ifstream or fstream object instead of the cin object. After writing information entered by the user to a file named afile.
These member functions are seekg "seek get" for istream and seekp "seek put" for ostream. The argument to seekg and seekp normally is a long integer. A second argument can be specified to indicate the seek direction.
The seek direction can be ios::beg the default for positioning relative to the beginning of a stream, ios::cur for positioning relative to the current position in a stream or ios::end for positioning relative to the end of a stream. The file-position pointer is an integer value that specifies the location in the file as a number of bytes from the file's starting location.
Exceptions provide a way to transfer control from one part of a program to another. This is done using a throw keyword. The catch keyword indicates the catching of an exception. It is followed by one or more catch blocks. Assuming a block will raise an exception, a method catches an exception using a combination of the try and catch keywords.
The operand of the throw statement determines a type for the exception and can be any expression and the type of the result of the expression determines the type of exception thrown. You can specify what type of exception you want to catch and this is determined by the exception declaration that appears in parentheses following the keyword catch.
If you want to specify that a catch block should handle any type of exception that is thrown in a try block, you must put an ellipsis, If we compile and run above code, this would produce the following result: Division by zero condition! Define New Exceptions You can define your own exceptions by inheriting and overriding exception class functionality. This returns the cause of an exception. Many times, you are not aware in advance how much memory you will need to store particular information in a defined variable and the size of required memory can be determined at run time.
This operator is called new operator. If you are not in need of dynamically allocated memory anymore, you can use delete operator, which de-allocates memory previously allocated by new operator. The new and delete Operators There is following generic syntax to use new operator to allocate memory dynamically for any data-type. Let us start with built-in data types. For example we can define a pointer to type double and then request that the memory be allocated at execution time.
Using the same syntax what we have used above we can allocate memory dynamically as shown below. If we compile and run above code, this would produce the following result: Constructor called! Constructor called! Destructor called! For example, you might be writing some code that has a function called xyz and there is another library available which is also having same function xyz. Now the compiler has no way of knowing which version of xyz function you are referring to within your code.
A namespace is designed to overcome this difficulty and is used as additional information to differentiate similar functions, classes, variables etc. Using namespace, you can define the context in which names are defined. In essence, a namespace defines a scope.
This directive tells the compiler that the subsequent code is making use of names in the specified namespace. Names introduced in a using directive obey normal scope rules. The name is visible from the point of the using directive to the end of the scope in which the directive is found. Entities with the same name defined in an outer scope are hidden. Discontiguous Namespaces A namespace can be defined in several parts and so a namespace is made up of the sum of its separately defined parts.
The separate parts of a namespace can be spread over multiple files. So, if one part of the namespace requires a name defined in another file, that name must still be declared. A template is a blueprint or formula for creating a generic class or a function. The library containers like iterators and algorithms are examples of generic programming and have been developed using template concept.
This name can be used within the function definition. You can define more than one generic data type by using a comma- separated list. All preprocessor directives begin with , and only white-space characters may appear before a preprocessor directive on a line.
You already have seen a include directive in all the examples. This macro is used to include a header file into the source file. Let us see important directives: The define Preprocessor The define preprocessor directive creates symbolic constants.
The symbolic constant is called a macro and the general form of the directive is: define macro-name replacement-text When this line appears in a file, all subsequent occurrences of macro in that file will be replaced by replacement-text before the program is compiled.
Now, if you check test. This process is called conditional compilation. The operator causes a replacement-text token to be converted to a string surrounded by quotes. There are signals which cannot be caught by the program but there is a following list of signals which you can catch in your program and can take appropriate actions based on the signal.
Whatever signal you want to catch in your program, you must register that signal using signal function and associate it with a signal handler. Going to sleep Interrupt signal 2 received. The raise Function You can generate signals by function raise , which takes an integer signal number as an argument and has the following syntax. In general, there are two types of multitasking: process-based and thread-based. Process-based multitasking handles the concurrent execution of programs.
Thread-based multitasking deals with the concurrent execution of pieces of the same program. A multithreaded program contains two or more parts that can run concurrently. Each part of such a program is called a thread, and each thread defines a separate path of execution. Instead, it relies entirely upon the operating system to provide this feature. This routine can be called any number of times from anywhere within your code. Here is the description of the parameters: Parameter Description thread An opaque, unique identifier for the new thread returned by the subroutine.
You can specify a thread attributes object, or NULL for the default values. It must be passed by reference as a pointer cast of type void. NULL may be used if no argument is to be passed. The maximum number of threads that may be created by a process is implementation dependent. Once created, threads are peers, and may create other threads. There is no implied hierarchy or dependency between threads. Otherwise, they will be automatically terminated when main finishes.
Each thread prints a "Hello World! Thread ID, 0 Hello World! Thread ID, 1 Hello World! Thread ID, 2 Hello World! Thread ID, 3 Hello World! When a thread is created, one of its attributes defines whether it is joinable or detached. Knjiga je podeljena u etrnaest glava, koje su ukratko opisane u nastavku teksta. Failure to do so is a violation of copyright laws. This tutorial may contain inaccuracies or errors and tutorialspoint provides no guarantee regarding the. In order to understand how this is accomplished, we need to.
Use the Gentran Integration Suite 4. This guide focuses on these installation tasks, including: Setting up the database. UNIX desktop operating system. Tight integration with hardware—from the sleek MacBook to the eight-core Mac Pro.
The history command is definitely useful in this case. Sams Publishing. It examines more advanced shell programming, advanced commands including awk and sed and regular expressions. Chapter 5 Systems Administration Theory This chapter exam. This book uses a single operating system as a concrete example to illustrate oper-ating system concepts.
In this authoritative work, Linux programm. This is a book about UNIX programming. It starts with basic concepts and ends with coverage of advanced topics. It is a self-teaching guide, and yet it functions as a UNIX reference book. The examples are short programs, each in. Kernel, drivers and embedded Linux development, consulting, training and support. If you discover any errors on our website or in this tutorial, please notify us at [email protected] i Contents About the Tutorial Net Framework Download Hadoop Tutorial - TutorialsPoint.
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