Comments in C++

February 14, 2023

Comments in C++

Here, in this section, we will discuss comments in  C++. Comments are used to insert meaningful descriptions or notes where ever required in the code so as to enhance readability and user understanding of the program.

  • Comments are statements in the program that are ignored i.e not executed by the compiler
  • Comments can be used anywhere, at any point, and any number of times in the program

Single Line Comments

They are used with 2 backslashes (//) everything after (//)is ignored by the compiler within that line
Program to demonstrate single Line comments
Run 
#include <iostream>
using namespace std;

int main()
{
    int a = 2, b = 3; // a, b are variables of type int 
    cout << a + b; //cout is present in std namespace
    
    return 0;
}

Output

5
  • Single line comments are always applicable in a line. if you don’t use a backslash in the next line they are treated as normal code and may result in an error
  • So you need to use //es in each line separately

C++ Introduction

History of C++

Structure of a C++ Program

Program to check armstrong number or not

Example :

Run 
#include<iostream>
using namespace std;

int main()
{
    cout << "Hello"; // this will print Hello
    this is not commented
    // this is commented 
}

Output

Compile time error

MultiLine Comments

  • The start with /* and end with */ .ie the block of code that falls between /* and */ is commented
  • They are also called as block comments
Program to demonstrate MultiLine comments
Run 
#include <iostream>

using namespace std;

/* Multiline comments in C++*/
int main()
{
    cout << "Demo";
    
    /* This is a multiline comment
    Lorem Ipsum is simply dummy text of the printing and typesetting industry. 
    Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, 
    when an unknown printer took a galley of type and scrambled it to make a type 
    specimen book. It has survived not only five centuries, but also the leap into 
    electronic typesetting, remaining essentially unchanged. It was popularised 
    in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, 
    and more recently with desktop publishing software like Aldus PageMaker including 
    versions of Lorem Ipsum.*/
}

Output

Demo
Single line comments cannot be closed in between i.e once you use a single line  comment again you cannot write normal code within that line, whereas multiline comments  can be closed in between and again you can write code within the same line

Example

Run 
#include <iostream>

using namespace std;

/* Multiline comments in C++*/
using namespace std;

int main()
{
    cout << "Hello "; /*multiline comment bw statements in same line*/ cout << "World";
    //you add statements in the same line when using single line comment
}

Output

Hello

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