 Hello friends, I am Naval Emul, working as an assistant professor in Department of Mechanical Engineering, Walsh and Institute of Technology, Solakpur. In this video, we are going to see the basics of C++. Learning outcomes, at the end of this session, students will be able to understand basic program of C++, content, sample C++ program, applications of C++. First line of the program is hash include iostream using namespace standard, then int main followed by the program inside the braces, double slash, sample C++ code, cout, insertion operator, then double inverted, hello world, semicolon, written 0, semicolon, the output for this program will be hello world. So we will see each and every statement in detail in the further slides. First hash include iostream, hash include is a pre-processor directive used to include header files. A header file contains declaration of functions, constants, variables and various classes. Header file iostream.h contains declarations of functions and classes that are used to perform input and output operations. The C++ standard has defined a new way to specify header files that do not use .h extension to file names. Files hash include iostream, hash include fstream, hash include string, where iostream, fstream and string etc are new style headers. All the declarations of functions, classes are present in global namespace standard. So new style headers are used along with global namespace standards. So we will see what is using namespace standards. Here iostream is one of a modern style header. The new style header do not specify file names, instead the simply specify standard identifiers that may be mapped to files by the compiler although they need not be. The new style headers are an abstraction that simply guarantees that the appropriate prototype and definitions required by the C++ library have been declared. The statement using namespace standards tells the compiler to use standard namespace. This is a namespace in which entire C++ library is declared. By using standard namespace you simply access the entire standard library. Third int main like C, C++ is a collection of functions. In the above example we have only one function, main execution of C++ program starts from main as a function. Fourth is comments, C++ introduces a single line comment. The symbol is double black backslash that is for a single line comment and for multi line comment or a block comment backslash asterisk then asterisk backslash. For block comment or multi line comment next is output operator. In the previous slides we have seen the program and the statement was cout insertion operator in the double inverted comma there is hello world. C++ new feature for handling input and output operators are called streams. Streams are abstraction that refers to data flow. C++ stream deals with sequence of characters, types of stream first is output stream, second is input stream. Cout insertion operator in the double inverted hello world then followed by the semicolon cause the string in quotation mark to be displayed on screen. This introduces two new C++ features and these features are as follows. First one is cout it is predefined object of standard output stream. Standard output stream represents the screen. Insertion operator or it is less than symbol this operator is known as insertion operator it inserts the content on the right side variable into the left hand side object. So lastly we will see what is return type of main in C++ main returns an integer value to operating system. The statement return 0 means your program has performed well as per expectations default return type for all functions in C++ int for example int main your program starts here and while the end we write return 0 it means that the program has performed well as per the expectations. We will see a small and simple program to find the average of two numbers. So hash include IO stream then the main program starts here that is int main int a, b float average here int and float other data types cout insertion operator enter two numbers then we are using c in for input and extraction operator a and b here when the user enters two numbers the two numbers are stored in a and b then the logic or formula is applied here that is average is equal to a plus b divided by 2. So the two numbers average is taken and that average is stored in avg variable again we are using cout cout the average of the two numbers then we call the average then we are using nl as a manipulator which means we are getting the cursor in the next line then we are using return 0 and finishing the program. Input for this program will be like enter two numbers 5 comma 4 the average of the numbers will be 4.5. So from this program we will see what is c in and extraction operator. So input operators the statement c in then extraction operator a 1 extraction operator a 2 causes program to wait for users to type in a number whose numbers will get placed into a 1 and a 2 your c in is a predefined object of standard input stream your input stream represents and keyboard. Extraction operator or greater than greater than symbol this operator is known as extraction operator it extracts the value from keyboard and assign it to variable on the right hand side second we will see cascading of input output operator the multiple use of insertion operator or extraction operator in one statement is called a cascading of input output operators. For example c out insertion operator we are using sum and we are calling sum and nl this example is for cascading of output operator c in extraction operator then a 1 followed by the extraction operator a 2 this is called cascading of input operators. Next applications of c++ c++ is a versatile language for handling very large program it is suitable for virtually any program in task including developing of editors compilers databases communication system and real life application since c++ allows us to create a hierarchy of related classes we can build special object oriented libraries which can be used by many programmers c++ is able to map real world problems properly the c part of c++ gives the language ability to get close to machine level details c++ program are easily maintainable and expandable when new features are added to be implemented they are added to the existing one references thank you.