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What is the basic structure of a C++ program?

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Structure of a C++ program

A C++ program is structured in a specific and particular manner. In C++, a program is divided into the following three sections:

  1. Standard Libraries Section
  2. Main Function Section
  3. Function Body Section

For example, let’s look at the implementation of the Hello World program:

#include <iostream>
using namespace std;
int main() {
cout << "Hello World!" << endl;
return 0;
}

Standard libraries section

#include <iostream>
using namespace std;
  • #include is a specific preprocessor command that effectively copies and pastes the entire text of the file, specified between the angle brackets, into the source code.

  • The file <iostream>, which is a standard file that should come with the C++ compiler, is short for input-output streams. This command contains code for displaying and getting an input from the user.

  • namespace is a prefix that is applied to all the names in a certain set. iostream file defines two names used in this program - cout and endl.

  • This code is saying: Use the cout and endl tools from the std toolbox.

Main function section

int main() {}
  • The starting point of all C++ programs is the main function.

  • This function is called by the operating system when your program is executed by the computer.

  • { signifies the start of a block of code, ​and } signifies the end.

Function body section

cout << "Hello World" << endl;
return 0;
  • The name cout is short for character output and displays whatever is between the << brackets.

  • Symbols such as << can also behave like functions and are used with the keyword cout.

  • The return keyword tells the program to return a value to the function int main

  • After the return statement, execution control returns to the operating system component that launched this program.

  • Execution of the code terminates here.

RELATED TAGS

c++
beginner
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Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

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