C++ Notes / PDF

C++ Notes / PDF

C++ is a statically typed, compiled, general purpose, case-sensitive, free-form programming language that supports procedural, object-oriented, and generic programming.

C++ is regarded as a middle-level language, as it comprises a combination of both high-level and low-level language features.

C++ was developed by BjarneStroustrup starting in 1979 at Bell Labs in Murray Hill, New Jersey as an enhancement to the C language and originally named C with Classes but later it was renamed C++ in 1983.

C++ is a superset of C, and that virtually any legal C program is a legal C++ program.

C++ Compiler:

This is actual C++ compiler which will be used to compile your source code into final executable program.

Most C++ compilers don't care what extension you give your source code, but if you don't specify otherwise, many will use .cpp by default

Most frequently used and free available compiler is GNU C/C++ compiler, otherwise you can have compilers either from HP or Solaris if you have respective Operating Systems.

C++ Basic Syntax

When we consider a C++ program it can be defined as a collection of objects that communicate via invoking each other’s methods. Let us now briefly look into what do class, object, methods and instant variables mean.

·         Object - Objects have states and behaviors. Example: A dog has states-color, name, breed as well as behaviors -wagging, barking, eating. An object is an instance of a class.

·         Class - A class can be defined as a template/ blue print that describe the behaviors/states that object of its type support.

·         Methods - A method is basically a behavior. A class can contain many methods. It is in methods where the logics are written, data is manipulated and all the actions are executed.

·         Instant Variables - Each object has its unique set of instant variables. An object's state is created by the values assigned to these instant variables.

C++ Program Structure:

Let us look at a simple code that would print the words Hello World.

#include

usingnamespacestd;

// main() is where program execution begins.

int main()

{

cout<<"Hello World";// prints Hello World

return0;

}

Let us look various parts of the above program:

·         The C++ language defines several headers, which contain information that is either necessary or useful to your program. For this program, the header  is needed.

·         The line using namespace std; tells the compiler to use the std namespace. Namespaces are a relatively recent addition to C++.

·         The next line // main() is where program execution begins. is a single-line comment available in C++. Single-line comments begin with // and stop at the end of the line.

·         The line int main() is the main function where program execution begins.

·         The next line cout<< "This is my first C++ program."; causes the message "This is my first C++ program" to be displayed on the screen.

·         The next line return 0; terminates main( )function and causes it to return the value 0 to the calling process.

Compile & Execute C++ Program:

Let’s look at how to save the file, compile and run the program. Please follow the steps given below:

• Open a text editor and add the code as above.
• Save the file as : hello.cpp
• Open a command prompt and go to the directory where you saved the file.
• Type 'g++ hello.cpp ' and press enter to compile your code. If there are no errors in your code the command prompt will take you to the next line and would generate a.out executable file.
• Now type ' a.out' to run your program.
• You will be able to see ' Hello World ' printed on the window.

$ g++ hello.cpp

$ ./a.out

HelloWorld

Make sure that g++ is in your path and that you are running it in the directory containing file hello.cpp.

You can compile C/C++ programs using make file. For more detail you can check Makefile Tutorial.

Semicolons & Blocks in C++:

In C++, the semicolon is a statement terminator. That is, each individual statement must be ended with a semicolon. It indicates the end of one logical entity.

For example, following are three different statements:

x = y;

y = y+1;

add(x, y);

A block is a set of logically connected statements that are surrounded by opening and closing braces. For example:

{

cout<<"Hello World";// prints Hello World

return0;

}

C++ does not recognize the end of the line as a terminator. For this reason, it does not matter where on a line you put a statement. For example:

x = y;

y = y+1;

add(x, y);

is the same as

x = y; y = y+1; add(x, y);

C++ Identifiers:

A C++ identifier is a name used to identify a variable, function, class, module, or any other user-defined item. An identifier starts with a letter A to Z or a to z or an underscore (_) followed by zero or more letters, underscores, and digits (0 to 9).

C++ does not allow punctuation characters such as @, $, and % within identifiers. C++ is a case sensitive programming language. Thus Manpower and manpower are two different identifiers in C++.

Here are some examples of acceptable identifiers:

mohdzaraabcmove_name  a_123

myname50   _temp   j     a23b9      retVal

C++ Keywords:

The following list shows the reserved words in C++. These reserved words may not be used as constant or variable or any other identifier names.......

C++ Notes / PDF