Preprocessor
Directive:
The preprocessor
directive in C++ begins with the character #. It is used to include necessary
header files in a C++ program before compilation. By using directives like
#include, the preprocessor copies the content of the specified header files
into the program, providing access to predefined functions and macros.
Header File:
A header file contains
function declarations and macro definitions for C++ built-in library functions
used in a program. When we include a header file in a C++ program using the #include
<filename.h> command, all the code inside the header file is included in
the program. This allows the program to access the functionalities and
definitions provided by the included header file during compilation.
Namespace std:
In C++, when we use the
statement "using namespace std", it eliminates the need to write
"std::" in front of standard commands throughout the code. The
"std" namespace contains all the classes, objects, and functions of
the standard C++ library. By using the "using namespace std"
directive, we can directly access the elements of the "std" namespace
without explicitly specifying it.
Definition/Declaration
Section:
The
definition/declaration section in a C++ program is used to define macros,
structures, classes, and global variables. These definitions allow us to use
these entities throughout the program, providing a convenient way to declare
and initialize variables or define custom data types.
Program Main Function
(Entry Point):
In C++, the main function
serves as the entry point of the program. It is a required function that has a
return type (usually "int") and, in some cases, accepts inputs via
parameters. The operating system calls the main function when the user runs the
program, initiating the execution of the program's code.
Main Function Return
Type:
In the latest C++
standard, the main function has an "int" return type. It indicates
that, upon successful completion, the C++ program will return an integer value.
The default return value is typically 0, indicating a normal execution of the
program.
Opening Brace:
The opening brace
"{", also known as the left brace, signifies the beginning of a block
of code. In C++, whatever code we write inside the main function or any other
block is written after the opening brace.
Body of Main Function:
The body of the main
function contains the actual code of the C++ program. It includes the
statements, expressions, function calls, and other instructions that define the
program's logic. The code written in the main function is executed when the
program runs.
Main Function Return
Value:
The return value of the
main function is used to indicate how the program exited. If the program
execution is normal and completes successfully, a return value of 0 is
typically used. Abnormal termination, such as errors, invalid inputs, or
segmentation faults, is usually indicated by a non-zero return value.
Closing Brace:
The closing brace
"}", also known as the right brace, marks the end of a block of code.
In C++, we use the closing brace to signify the completion of the main function
or any other block of code.
Function Definition
Section:
The function definition
section is where we define functions to fulfill specific requirements. It
allows us to declare the function's name, return type, parameters, and the code
block that defines the function's behavior. Functions defined in this section
can be called and utilized throughout the program.
Note: The above
information provides a general understanding of the terminologies in C++
programming. It is recommended to refer to official C++ documentation and
resources for more comprehensive knowledge and usage guidelines.
