Structure of C++ programs info

Structure of C++ programs info

• Preprocessor is a collection of special statements (program), called "Directives" which are executed before the compilation process. Whenever a C++ program is compiled, the preprocessor first examines and scans it for compilation. The second main thing that a preprocessor does is to process all the preprocessor directives. All lines that begin with a "hash(#)" character are preprocessor directives.
• for example:
• #include<iostream.h>
•  All C++ programs are composed of different units or functions, in which main() is one of them, which must be present in every C++ program. It is the main() function which is called by the operating system when name of the program is typed at the OS prompt. Since normally no arguments are passed to main() and main() does not return a value, it frequently looks like this
• "void main(void)".
• "void" means no data type at all. It is generally used with functions that return no values. Empty parenthesis are usually used to indicate a void parameter list, which means the same thing as "void". So "main()" is equivalent to "void main(void)".
•  All functions are consist of two parts,
• 1. Function header
• 2. Function body
• Function header consists of the type and the name of the function. Every function in a program must have a unique name in the program with a set of parenthesis immediately following it. This set of parenthesis helps to distinguish functions from variables. For example
• void AVERAGE()    int FACTORIAL()     void REPORT()
• These three are the examples of function headers.
• The function body or function block consist of the C++ statements that the function performs. C++ statements are free format, they may appear anywhere on a line. The compiler does not care. It only needs blanks to separate symbols and semicolons to separate statements. These statements must be enclosed within a pair of braces.
• # include<headername.h>
• void main()
• {
• statement1;
• statement2;
• }