Structure of a C++ Program | Components of C++ Program
Structure of a C++ Program contains different parts as follows
- Documentation Section
- Link Section
- Definition Section
- Global Declaration Section
- main() function Section
- Subprogram Section [User Defined Function Section]
In this section we can specify the name of program along with details of developer and other details as per requirement. We can use comments for documentation section.
/* Program to show the use of cout<< statement*/
Comments start from /* and end with */
This section includes header files and performs conditional compilation of a C++program. This section also links the program with library of C++.
We need to include iostream header file in a program if we want to use cout, cin and other input output operations in a C++ program .
This section can be used to define the macros and symbolic constants in a C++ program.
i. #define PI 3.141
Symbolic constant PI has been declared containing value 3.141. Its value can’t be changed during program execution.
ii. #define perimeter(r) 2*3.141*r
Macro with name perimeter has been defined in this example . It contains one argument. When this macro is invoked it will return perimeter of circle depending upon the value of argument r passed to it.
Global Declaration Section
We can declare global variables and user defined types like structures and classes. in this section. Global variables can be accessed and used by multiple functions in a program. Any changes made to them are available in entire program.
main() Function Section
Every program has a main() function. This function has two parts.
– Declaration Part: we can declare local variables here. They can be of different data types. Values of these variables can change and remain active till the end of main() function.
– Executable Part : We write the C++ statements in this part. It can contain any number of executable statements of C language.
We can define user defined functions in this section. These functions can be invoked by the main() as well as other functions. These functions can also be defined before main() function.