C / C++ / MFC

2-Dec-08 1:47

Hi All,
i was talking to a guy .. who asked about return 0 or return 1
i told him that it return 0 means code have no run time error and if its return 1 it has some error ...

he asked me from where its coming .. i told its coming from comipler ...

but my answer was not as per his expectation can you please more clerify what should i answer in such cases..

vikas da

gayatri.neelema2-Dec-08 1:50

2-Dec-08 1:50

I think the return value always comes from your code.
I think the compiler only compiles the code and gives you the .obj file and does not return any value.

tasumisra2-Dec-08 1:56

2-Dec-08 1:56

lets see a simple code

int main ()
{
  return 0;
}

in above return 0 is defintly user defined .. is there no relation of this return 0 with compiler ...

i am not very sure .. Frown | :(

vikas da

Jijo.Raj2-Dec-08 2:20

Jijo.Raj

2-Dec-08 2:20

Well, in C/C++, 0 means false and non-zero means true. For instance, in platform SDK,

#define FALSE 0
#define TRUE 1

But that is not the same with application exit codes. If the application exit code is 0, then its treated as executed successfully, or else its a warning or error. Check this link[^].

In summery, don't confuse with zero in C/C++ and that of standard DOS exit codes. Both have different meaning. Big Grin | :-D

Regards,
Jijo.

_____________________________________________________

http://weseetips.com[^] Visual C++ tips and tricks. Updated daily.

tasumisra2-Dec-08 2:24

2-Dec-08 2:24

Thanks Jijo...

so while executing an application or better to say a programm where these DOS Exit codes comes in picture....
1.During comilation..?
2.During run time..?

and how they are handeled.. Frown | :(

Thanks again...

vikas da

Jijo.Raj2-Dec-08 2:42

Jijo.Raj

2-Dec-08 2:42

Ofcourse during runtime. Dos execute code comes to scene while executing the applications. Seems you need more explanation.

Dos exit code is the return code that every dos application [as well as windows applications] should return. And as per standard, 0 means its executed successfully. The exit code of last executed application is stored in environment variable - ERRORLEVEL. For instance, take the command prompt and type these two commands.

copy blabla balalala
echo %errorlevel%

Since the copy command failed, you can see return code as 1. if you execute a successful command it should return 0.

For C/C++ compiled application, exit code is the integer returned by main() function. If you want to make the exit code of you application as 1 if success, then return 1 from main(). Hope its clear now. Smile | :)

Regards,
Jijo.

_____________________________________________________

http://weseetips.com[^] Visual C++ tips and tricks. Updated daily.

CPallini2-Dec-08 2:39

CPallini

2-Dec-08 2:39

Return value is usually a meaningful info given back to the caller, hence the exact meaning of '0' or '1' (or whatever) is (usually again) a matter of convention between the caller and the called. For instance the return value of the 'special' C main function is, by convention 0 on success and nonzero on failure.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

David Crow2-Dec-08 3:17

2-Dec-08 3:17

tasumisra wrote:
i told him that it return 0 means code have no run time error and if its return 1 it has some error ...

There is nothing offical that says it has to be this way. It's all up to the sender and receiver as to what the values mean.

"Love people and use things, not love things and use people." - Unknown

"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

tasumisra2-Dec-08 4:07

2-Dec-08 4:07

thanks you all for replies..

i am still not able to understand .. who is this sender reciever...how this communication is happening..

Thank you...

vikas da

David Crow2-Dec-08 4:16

2-Dec-08 4:16

tasumisra wrote:
who is this sender reciever...

This is a very basic programming question. In fact, it is communication in its simplest form. When two objects communicate, the "codes" they send back and forth only have meaning to the two objects involved. While some codes are standard, others are not. For example, code 5 from the computer in a Chevrolet may indicate an error in the oxygen sensing unit, while code 5 from the computer in a Dodge may indicate an error in the transmission.

What exactly are you fishing for?

"Love people and use things, not love things and use people." - Unknown

"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

CPallini2-Dec-08 6:00

CPallini

2-Dec-08 6:00

DavidCrow wrote:
For example, code 5 from the computer in a Chevrolet may indicate an error in the oxygen sensing unit, while code 5 from the computer in a Dodge may indicate an error in the transmission.

Oh, US are great!

The 'computer' of my car has just a boolean return value: the fuel warning light...
Big Grin | :-D

tasumisra3-Dec-08 17:40

3-Dec-08 17:40

thanks alot...i understand now...

vikas da

invalid registry entries

gayatri.neelema2-Dec-08 1:44

2-Dec-08 1:44

Hi,
I was wondering how can i determine if there a registry key is valid or not.

Rajesh R Subramanian2-Dec-08 1:51

Rajesh R Subramanian

2-Dec-08 1:51

Well, that largely depends on your definition of "valid".

It is a crappy thing, but it's life -^ Carlo Pallini

gayatri.neelema2-Dec-08 1:56

2-Dec-08 1:56

Thats fair enough.If i want to access the registry key value then it should allow me to access it.
Something which registry cleaner software uses to determine whether to delete the registry key or not.

David Crow2-Dec-08 3:25

2-Dec-08 3:25

gayatri.neelema wrote:
Something which registry cleaner software uses to determine whether to delete the registry key or not.

Keys and values are deleted based on a set of rules. And a rule used for one key may not be valid for some other key. Some keys/values may refer to file system paths. If the specified path does not exist, then the key/value may be invalid. Other keys/values refer to GUIDs that may not exist. If a key/value does not refer to anything or just has a value (e.g., 17), can it be deleted? Only the author of such knows for sure.

"Love people and use things, not love things and use people." - Unknown

"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

gayatri.neelema2-Dec-08 18:59

2-Dec-08 18:59

hey thanks for your reply.
But even rules cannot be formed just like tat.
I was curious to know if there were any such algorithm .so that i can use it.

Rajesh R Subramanian2-Dec-08 20:17

Rajesh R Subramanian

2-Dec-08 20:17

Well, there's no such thing called "registry cleaning" and most of those software are nothing more than a pile of crap.

As David clearly stated, how could anyone else other than the author (the app who wrote the key and values) possibly know that the key is "invalid" or "unwanted"? And there is no such algorithm available which decides this. If you need one, you must think of all the possibilities and devise your own algorithm.

A slight mistake that a registry cleaning software can cause devastating results. May be on operating systems like Win95 or 98, you could possibly get a very marginal benefit by deleting the registry keys that are unused. But with more recent versions, the OS is smart enough and you will almost get NO benefit just be deleting some registry keys that aren't used. If you have a different opinion (with some kind of proof or benchmarking tests done), I'll be interested in hearing from you.

After all, if you don't know much about how and what kind of cleaning operations should be performed on the registry, you must not be writing such a software.

It is a crappy thing, but it's life -^ Carlo Pallini

David Crow3-Dec-08 3:59

3-Dec-08 3:59

While it's not an answer to your question, take a look at this article. It shows how to remove registry entries that are known to be bad. That should clue you in as to why you can't just willy nilly remove registry entries without knowing what they are for.

"Love people and use things, not love things and use people." - Unknown

"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

gayatri.neelema3-Dec-08 22:14