C++ Basics.pdf

C++ Basics Course Code: CC 113 (B) Course Title: Introduction to Programming (C++) Prepared by: Alvin Herrera, Instructor 1 Structure of a program Probably the best way to start learning a programming language is by writing a program. Therefore, here is our first program: Struct...

C++ Basics Course Code: CC 113 (B) Course Title: Introduction to Programming (C++) Prepared by: Alvin Herrera, Instructor 1 Structure of a program Probably the best way to start learning a programming language is by writing a program. Therefore, here is our first program: Structure of a program The first panel shows the source code for our first program. The second one shows the result of the program once compiled and executed. The previous program is the typical program that programmer apprentices write for the first time, and its result is the printing on screen of the "Hello World!" sentence. It is one of the simplest programs that can be written in C++, but it already contains the fundamental components that every C++ program has. Structure of a program // my first program in C++ This is a comment line. All lines beginning with two slash signs (//) are considered comments and do not have any effect on the behavior of the program. The programmer can use them to include short explanations or observations within the source code itself. In this case, the line is a brief description of what our program is. Structure of a program #include Lines beginning with a hash sign (#) are directives for the preprocessor. In C++, a directive is a line of code that begins with the # symbol and instructs the preprocessor to perform a specific action before compilation. The preprocessor is a part of the compiler that processes the source code before it reaches the actual compiler. They are not regular code lines with expressions but indications for the compiler's preprocessor. In this case the directive #include tells the preprocessor to include the iostream standard file. This specific file (iostream) includes the declarations of the basic standard input-output library in C++, and it is included because its functionality is going to be used later in the program. Structure of a program using namespace std; All the elements of the standard C++ library are declared within what is called a namespace, the namespace with the name std. So in order to access its functionality we declare with this expression that we will be using these entities. This line is very frequent in C++ programs that use the standard library, and in fact it will be included in most of the source codes. Structure of a program int main () This line corresponds to the beginning of the definition of the main function. The main function is the point by where all C++ programs start their execution, independently of its location within the source code. It does not matter whether there are other functions with other names defined before or after it - the instructions contained within this function's definition will always be the first ones to be executed in any C++ program. For that same reason, it is essential that all C++ programs have a main function. Structure of a program int main () The word main is followed in the code by a pair of parentheses (()). That is because it is a function declaration. In C++, what differentiates a function declaration from other types of expressions are these parentheses that follow its name. Optionally, these parentheses may enclose a list of parameters within them. Right after these parentheses we can find the body of the main function enclosed in braces ({}). What is contained within these braces is what the function does when it is executed. Structure of a program cout