Basic Structure of C++ Program - The Coding Shala

Home >> Learn C++ >> Basic Structure of C++ Program

Basic Structure of the C++ Program

The basic structure of the C++ program is as follows - 
Basic Structure of C++ Program - The Coding Shala
C++ program can be simplified into two parts - first, writing a program in a text editor and save it with the correct extension. c++ program can be save with .cpp, .c, .cp extension.
second, compiling your c++ program using a compiler or online IDE to check the output of your program.

Let's look the below c++ code that will print 'Hello World' as output -  

1:  //This is comment inline comment  
2:  /* This is also comment mulitine comment  
3:   C++ program to display "Hello World"  
4:   end of multiline comment */  
5:  #include<iostream> // this include header file for input output functions  
6:  using namespace std;  
7:  // main function starts where the execution of program begins  
8:  int main()  
9:  {  
10:    cout<<"Hello World";  // prints heelo world  
11:     //semicolon is used as statement terminater.  
12:    return 0;  
13:  }  

Output : 
1:  Hello World  

Now, let's understand every line of the c++ program - 

In C++ there are two types of comment, single-line comment, and multiline comments. The compiler always skips comments. Comments are used for additional information about the program. single-line comments start with '//' without quotes and multiline comments come between '/* .. */'. In our program line no. is contain single line comment and from line no. 2 to line no. 4 is a multiline comment.

line 5, the #include directive is used to include a file. Here #include<iostream>, tells the compiler to include the standard iostream file which contains a declaration of all the standard input/output library functions. 

line no. 6 - using namespace std, here we are going to use std namespace where features of the c++ standard library, such as string, vectors, etc. are declared means we can write just cout instead of std:: cout when calling the operator cout defined in the namespace std. we will learn more about namespace in the following chapters. 

line no. 8 - int main(), execution of every c++ program begins with the main() function so every c++ program must have a main() function. this line is used to declare the main function which returns data of integer type. It is never a good idea to use "void main()" or "main()" instead of "int main()" as it does not confirm standards. it may or may not be allowed by some compilers.

line no. 9 to 13 - between { .. }, '{' indicates the beginning of the main function and '}' the closing braces indicates the ending of the main function. this is the body of the main function. 

cout<<"Hello World";, this is a statement, every statement is meant to perform some task here, this display output 'Hello World' without quotes. 

return 0; this is also a statement. this statement is used to return a value from a function and indicates the finishing of a function. 

Every program is typically composed of 3 basic elements: expressions, statements, and functions. The most common type of instruction in a program is the statement. this is the smallest independent unit in the language for eg. int x; is a statement. An Expression specifies a computation to be performed and statements are typically grouped into units called functions. A statement is a complete sentence that tells the compiler to perform a particular task and expression is a mathematical entity that evaluates to a value.

Compile and Execute C++ Program 

In IDE we can directly compile and run the c++ program by simply run it. To compile the C++ program in command prompt follow the below steps - 
  • Open a text editor and write code inside it 
  • Save the file with a correct extension for eg. Hello.cpp
  • open the command prompt and go to the directory where the file is saved.
  • To compile code type 'g++ Hello.cpp' without quotes and press enter. here you will get to know errors if any errors are there otherwise it would generate a.out executable file.
  • To run the program type 'a.out' without quotes. it will display the outputs.

Other Posts You May Like
Prev<< Introduction to C++                                    NEXT >>Data Types and Modifiers in C++
Please leave a comment below if you like this post or found some error, it will help me to improve my content.


Popular Posts from this Blog

Shell Script to find sum, product and average of given numbers - The Coding Shala

Shell Script to Display the digits which are at odd positions in a given 5-digit number - The Coding Shala

Richest Customer Wealth LeetCode Solution - The Coding Shala

Add two numbers in Scala - The Coding Shala

LeetCode - Shuffle the Array Solution - The Coding Shala