Structure of a C++ Program
A program is a sequence of logical
instructions that can be executed by a compiler in a computer. All programs are
written to solve any problem by programming language. The best way to learn a
programming starts from the root of that language. Therefore, here we will try
to write our first program:
Step-1:
// This is my first program in C++
# include <iostream>
using namespace std ;
int main ()
{
cout << " Hello C++ Programming \n" ;
return 0;
}
Step-2:
Output:
Hello
C++ Programming
The first step shows the source code
for our first program. The second step shows the result of the program once
compiled and also executed. The source code writing style and way of compiling
a source code (program) depends on the version of compiler and development
environment installed in your computer. The previous program is the typical
program that programmer trainee writes for the first time in his/her education
life. Apparently the result on screen is “Hello C++ Programming”.
The substantial things is it is
contains the fundamental components that every C++ program has. Maximum person
tries this easy program by reading a blog or book. We are going to look line by
line at the code we have just written:
// my first program in C++
This line is used for showing
comments. Any lines beginning with two slash signs (//) are considered
comments. Comments lines do not have any effect on the behavior of the program.
Generally, the programmer uses them to include short explanations or
observations within the source code itself.
#include <iostream>
The preprocessor are directed by the
hash sign (#). Generally some lines are begins with # symbol at the top of the
source code. In this case the directive #include<iostream> tells the
preprocessor to include the iostream standard file. The iostream file 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.
using namespace std;
The namespace consists of all the element
belongs to standard C++ library. The namespace is called by std. So, if we like
to use the functionality belongs to std, we must declare the above mention
expression as like: using namespace std;
The expression must be ended with semicolon
(;). It tells the C++ compiler to apply the
prefix std::
After using that prefix, names will
be usable those need prefixes. It allows us to use cout
in place of std::cout. This makes larger
programs easier to read.
int main ()
This line indicates that main function
started. All C/C++ program need main() function
to start the program body. C/C++ program must have a main
() function and under it all the lines of source code will be enclosed
by an opening and closing curly braces ({}). The
required parenthesis that follows the word “main” indicates that it is a
function. The keyword int is the name of data type in C++. It stands for “integer”. It is used here to indicate the return type
for the main() function.
cout << "Hello C++ Programming";
The above line is a perfect C++
statement. The cout
represents to the standard output stream in C++ and its duty is to print/show
output to the user’s screen. Here, it says to send the string “Hello C++ Programming” to the standard output stream.
The single symbol << represents the C++
output operator. The characters enclosed in quotation marks "" are called string. This displays on the
output device, which is usually the computer screen. It usually happened when
any statement executes. The last two characters
\n represents the newline character. When the
output device encounters that character, it advances to the beginning of the
next line of the next on the screen. Finally, note that every program statement
must end with a semicolon (;)
return 0;
Return
is optional for the main () function in
Standard C++. We include it here only because some compilers expect it to be
included as the last line of the main () function.
“Return 0” means main()
will not return anything to any other function. “Return
1” means main() function will return
some value according to data type mentioned in main()
function prototype declaration section. Here “1”
means true and “0” means false.
