Difference between Bottom-up Approach (in C++) and Top-down Approach (in C)...

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2.52/5 (4 votes)

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Hi all,

I am very confused about the approaches used by C and C++ languages.
I know C uses "Top Down" while C++ uses "Bottom Up".
But i don't know why. I mean i am not getting the proper explanation.

Somewhere i read:

First thing Top down and bottom up are designing approaches.
As simple, in top down approach,first we are designing the
main module(i.e main function) and in that we will decide
what all other modules to be include then we will design all
other sub modules..this approach is used C prog language.

In bottom up approach, just contrast to top down,first we
design all the sub modules related to application then we
design main module and in that we will decide what are the
modules to be include.. for ex: we can design any no of
classes and in main only required classes and their
functions can be used ...this approach is used in c++ ......

But i am not sure that this would be the proper answer.

Is there any other reason??

And what about C# and JAVA??

Posted 29-Nov-13 9:57am

Atul Khanduri

Updated 30-Mar-18 0:54am

v2

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Comments

Sergey Alexandrovich Kryukov 29-Nov-13 16:09pm

Why are you asking us? Ask the guy who had written all that trash...
Sorry, I down-voted the answer, due to lack of the logic in the way you approach to learning things. You should not take what you read for granted and ask question assuming too much.
—SA

Maciej Los 29-Nov-13 18:11pm

:laugh:

Atul Khanduri 29-Nov-13 18:33pm

I think its no need to laugh, because one of the use of code-project is to ask your queries which you faced, either from code-project itself or from any other article or sites....
And for more read below comments....

Maciej Los 29-Nov-13 18:36pm

I'm laughing from Sergey's comment. I'm not laughing from your question. Are we clear, now?

Atul Khanduri 29-Nov-13 18:37pm

Yup....:-)

Maciej Los 29-Nov-13 18:33pm

Autul Khanduri, in my opinion, solution no. 1 deserves for accepting as an answer. Please, accept it.

Atul Khanduri 29-Nov-13 18:39pm

Okay.
I'll accept both of these solutions.:-)
And BTW its Atul Khanduri not Autul Khanduri(Just Saying)...;-)

Maciej Los 29-Nov-13 18:40pm

Sorry, my mistake ;)

Atul Khanduri 29-Nov-13 18:42pm

Okay sir, its no problem....:-)

Maciej Los 29-Nov-13 18:46pm

Your name is very interesting: Atul[^]. Try to find mine ;)

Atul Khanduri 29-Nov-13 20:46pm

Yup, its interesting...
And i'm not able to find your name their...:(
But i searched and now i know that you are from Poland and meaning of your name is "gift of God"....
Pretty interesting....

Maciej Los 30-Nov-13 11:43am

;)

Atul Khanduri 30-Nov-13 13:49pm

:)

3 solutions

Solution 3

I agree with the others that your premise is incorrect on several levels.

In my opinion, regardless of what you are developing, what language is used, what tools you use, you should design from the top down and implement from the bottom up.

Posted 29-Nov-13 12:48pm

PIEBALDconsult

Comments

Maciej Los 29-Nov-13 18:50pm

Interesting point of view ;)

Stefan_Lang 4-Dec-13 7:31am

I agree this is the ideal, but unfortunately this ideal is also the reason for analysis paralysis: You pretty much need to design everything to the smallest detail before starting to program when using this approach! If the project is anything but trivial, you'll never finish the design phase because you always discover more details and special cases - and if it's not you, someone will change the specification before you're done.

PIEBALDconsult 4-Dec-13 8:46am

Sure, if you don't know what you're doing.

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CPallini · Accepted Answer · 2013-11-29T10:08:00

Solution 1

Quote:
I know C uses "Top Down" while C++ uses "Bottom Up

That is false.
C and C++ programming languages do NOT use neither bottom-up nor top-down approach. Bottom-up and top-down approaches are techniques the developers could use for solving problems. For instance some parsers are bottom-up while others are top-down.
Both C and C++ are well suited for using both the approaches (they are well suited for using none of them as well).

Posted 29-Nov-13 10:08am

CPallini

Comments

Sergey Alexandrovich Kryukov 29-Nov-13 16:19pm

Strictly speaking, not only this is false, rather it is a set of words, not really a comprehensible statement with some certain sense. This is what I call blah-blahology, a pseudo science, or imitation of science. My 5, but...
Please see also my Solution 2, where I try to go a bit deeper...
—SA

Maciej Los 29-Nov-13 18:12pm

+5!

Atul Khanduri 29-Nov-13 18:39pm

My vote 5....:-)

Sergey Alexandrovich Kryukov · Accepted Answer · 2013-11-29T10:16:00

Solution 2

Please see my comment. Do you understand that you are doing wrong thing? You are reading some book and perceive what is written as if it was the law of nature. It is not. This is just some thoughts reflecting the way the author of this book or article looks at things. I would say, it just reflects the author's fantasy.

And then you are asking us, not even giving any links.

In fact, top-down and bottom-up approaches are not related to any specific language, and neither C nor C++ dictates or encourages any of these approaches. Moreover, neither top-down nor bottom-up approach, taken in any pure form, can provide a smooth and self-consistent method of development software. None of those over-simplified schemes can provide it. At best, it is always a combination. And any reasonable software development process is always much more complex and at the same time much more balanced than any of such approaches. First of all, it is always iterative, at least to some degree.

You need to apply much more critical thinking, just thinking and common sense while reading literature.

—SA

Posted 29-Nov-13 10:16am

Sergey Alexandrovich Kryukov

Updated 29-Nov-13 10:22am

v4

Comments

Atul Khanduri 29-Nov-13 16:31pm

It was asked in one of my interview, that's why i questioned here...
I googled it and found the same(that c uses Top-down and C++ uses Bottom Up) in so many sites.
And after reading those, i confused and asked here.

Here are the links where i got that information:

http://www.allinterview.com/showanswers/234.html
http://forums.asp.net/t/1891629.aspx
http://in.answers.yahoo.com/question/index?qid=20100625012803AAz7wpa
http://wiki.answers.com/Q/What_is_top_down_approach_in_c_-_programming#slide1

And many more...

Sergey Alexandrovich Kryukov 29-Nov-13 16:46pm

Here is my advice: stop reading trash written by incompetent people. Yes, there is more... Isn't it obvious: there is always more trash than something valuable.

I can even explain why those people are incompetent: helping to prepare for interviews is a wrong idea in principle. They either waste time or fool people trying to make some money. You don't need preparations for interviews; you need knowledge and experience which only comes with study, learning and practice. There is no other way around. Not only reading interview questions and answers is a waste of time, it can create false knowledge. If you want our help, you should stop reading all that trash and refer it.

—SA

Atul Khanduri 29-Nov-13 17:10pm

Yup i know, i never used to read any question to prepare for interview. But when he(interviewer)asked me this question(that from C and C++, which one uses Top-Down Approach and which one uses Bottom-Up Approach) then only i searched. Even i don't read any article related to this....:-)

Sergey Alexandrovich Kryukov 29-Nov-13 18:20pm

I understand. Very good. Will you accept the answer formally then (green "Accept" button)?
—SA

Atul Khanduri 29-Nov-13 18:23pm

Ya sure...
And i think you down-voted my question, which i dont think it is...!!!
Anyway thanks...:-)

Maciej Los 29-Nov-13 18:13pm

Good advice! In other words: holy words!

Stefan_Lang 4-Dec-13 7:59am

Maybe you should learn to read and interpret the results of your searches. None of your links imply what you are saying:

The first is a discussion of the question which happens to be in a C++ related forum, but is not inherently linked to the language - nor does it state whether or not C++ programming prefers either.

In the second link, only the original poster implies the relation as you did here - the responses however point in the right direction. Unfortunately the original poster neither understood nor properly read these answers as can be seen from his follow-up question...

The third link, while referncing C and C++, doesn't draw a connection between those languages and the top-down/bottom-up approach. Nor do the responses.

The last link provides a specialized and inaccurate response to a different question. It doesn't imply a relation to programming language either, although the question mentions C.

Overall, since all of these links only post to discussions of people of unknown expert status, you can't even be sure how accurate the answers and information given are. You should be checking technical articles instead to find reliable information!

Sergey Alexandrovich Kryukov 4-Dec-13 9:28am

Good points. Maybe you better quote these links in a separate answer and then put your comment in it. This is a very basic and sound advice on how to use one's brains while reading... :-)
—SA

CPallini 29-Nov-13 16:51pm

5.

Sergey Alexandrovich Kryukov 29-Nov-13 18:20pm

Thank you, Carlo.
—SA

Maciej Los 29-Nov-13 18:12pm

+5!

Sergey Alexandrovich Kryukov 29-Nov-13 18:20pm

Thank you, Maciej.
—SA

Tom Marvolo Riddle 4-Dec-13 2:57am

Sure +5.

Sergey Alexandrovich Kryukov 4-Dec-13 3:06am

Thank you very much.
—SA