What is the relationship between iostream and namespace std

0 votes

I am currently using Teach Yourself C++ in 21 Days, Second Edition book to learn about C++ coding, along with Microsoft Visual C++ 2010 Express. At the end of Chapter 1, there is a small exercise about writing and compiling the following code:

#include <iostream>

int main ()
{
    cout << "Hello World!\n";
    return 0;
}

Quite simple, right? However to my surprise the code would not compile, due to this error:

error C2065: 'cout' : undeclared identifier

I began scouring the Web, and soon found some solutions here. Turns out I had to add using namespace std; to my code!

However there was no mention of namespaces in the book, so I figured the book is outdated. (It uses #include <iostream.h> pre-processor directive!) After some more Web research I found a lot of information about namespaces, namespace std, along with some historical background on <iostream.h> and <iostream>, and all this flow of new information is quite confusing to me. (Not to mention all the unnecessary Google results about medical STDs...)

So here are some questions I've got so far:

  1. If I am including the iostream library, why is a namespace needed to find cout? Is there another cout somewhere that could cause a name clash? If someone could provide a diagram for this, that'd be great.

And as a bonus, some historical background:

  1. What exactly was iostream.h before it was changed to iostream?

  2. Did namespace play a part in this change?

Sep 22, 2022 in Others by gaurav
• 23,260 points
927 views

No answer to this question. Be the first to respond.

Your answer

Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.

Related Questions In Others

0 votes
0 answers

What is the difference between iostream , stdio.h and conio.h header files in c++?

I am confused between all these three ...READ MORE

Sep 23, 2022 in Others by gaurav
• 23,260 points
1,535 views
0 votes
1 answer

What is the difference between hadoop and google analytics ?

I will try and answer this as ...READ MORE

answered Aug 22, 2018 in Others by Frankie
• 9,830 points
1,630 views
+1 vote
1 answer

What is the difference between Dark Web and Deep Web?

The content that which you cannot find ...READ MORE

answered Feb 6, 2019 in Others by Priyaj
• 58,020 points
1,204 views
+1 vote
2 answers

What is the different between xml and json?

These are the differences:   It is JavaScript Object ...READ MORE

answered Feb 7, 2019 in Others by Junaid
1,600 views
0 votes
1 answer

What is the difference between BASH and DOS?

The major difference between the BASH and ...READ MORE

answered Mar 8, 2019 in Others by Nabarupa
17,018 views
0 votes
1 answer

What is the difference between loadash and underscore

Loadash makes iterating arrays, strings, and objects easy in ...READ MORE

answered Jun 21, 2019 in Others by sunshine
• 1,300 points
1,100 views
0 votes
0 answers

Is hiding implementation detail Encapsulation or Abstraction?

I have seen some people defining abstraction ...READ MORE

May 6, 2022 in Java by narikkadan
• 63,600 points
3,185 views
0 votes
1 answer

Why would anyone use set instead of unordered_set?

Unordered sets must compensate for their O(1) ...READ MORE

answered Jun 1, 2022 in C++ by Damon
• 4,960 points
2,962 views
0 votes
1 answer

Why is "using namespace std;" considered bad practice?

This has nothing to do with performan ...READ MORE

answered Jun 1, 2022 in C++ by Damon
• 4,960 points
908 views
0 votes
1 answer

What is a smart pointer and when should I use one?

A smart pointer is similar to a ...READ MORE

answered Jun 2, 2022 in C++ by Damon
• 4,960 points
489 views
webinar REGISTER FOR FREE WEBINAR X
REGISTER NOW
webinar_success Thank you for registering Join Edureka Meetup community for 100+ Free Webinars each month JOIN MEETUP GROUP