What is the functionality of this method?what are possibility problems,Bugs?

Question

1.00/5 (4 votes)

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C++

void copy(int *s,int *d,int slength){
int i=0;
for(i=0;i<slength;i++){>
d[i]=s[i];
}

}

Posted 25-May-12 23:52pm

eng.Fadialia

Updated 26-May-12 0:02am

Mehdi Gholam

v2

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Comments

Mehdi Gholam 26-May-12 6:02am

Sound like homework.

Sandeep Mewara 26-May-12 13:19pm

+1 homework...

3 solutions

Solution 3

Ignoring CPallini's rather complete answer and the fact it's either homework or a job interview question how would YOU solve the problem? Apart from asking online about it that is.

Say you can't work out what the functionality or problems with this code are. Do what most programmers would do who haven't been able to reason about what happens with the source code and:

- write a set of tests for the function. Be systematic - try sticking zeroes in for -each parameter in turn, maybe a few random values. As there are pointer parameters try pointing at different arrays of various sizes. Try small values of slength, try massive values.

- run the tests and see where they fall over. When you see what crashes see what happens to the code under a debugger.

- look at the function name, bit of a pointer (pardon the pun) there. Find standard functions in the C or C++ runtime libraries with similar signatures and functionality. Look them up online and see what their limits are.

FFS read about it, think about it, try it!

End of sermon, you can stop reading now.

PS: This is the sort of problem that mothers give their children when they want them to grow up to become Java programmers.

Posted 26-May-12 20:38pm

Aescleal

Solution 1

Certainly there is no problem with this function. What this function does is it copies elements(here integers)of a source array to a destination array.
So, tell us what happened, I mean if you have any problem with this function what is it?
I am sure the error would occur only because of parameters passed into the function, since they are pointers. You need to handle them carefully. You can face problems if your pointer was not initiated properly or and many more issues.
So tell us what problem have you encountered in using this function?

Posted 26-May-12 2:08am

stib_markc

Comments

eng.Fadialia 26-May-12 8:23am

Thank you very much..but I haven't any problems,just I want to know generally possible problems(bugs).
Can you demonstrate with example how pointer is a possible problem?

stib_markc 28-May-12 0:34am

Pointer or any possible entity in a language or language itself is never a problem. The problem is human perception and less knowledge. If you use pointer correctly then no problem will arise and also logic will be easy to implement. So, if you want to know what possible errors are with pointers, start writing some programs and find out if any errors and then post here if you cannot understand why error is happening. For more about pointers, try googling and after some basic tutorials look up this link
Pointers Usage in C++: Beginners to Advanced[^]

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CPallini · Accepted Answer · 2012-05-26T03:08:00

Solution 2

The function (apparently it is not a method) copies slength int values from the source memory area (pointed by s) to the destination memory area ( pointed by d).
The function (implicitely) assumes that:

s is a valid pointer to a memory area of size equal to (or greater than) slength.
As well, d is a valid pointer to a memory area of size equal to (or greater than) slength.
The memory areas pointed by s and d don't overlap.

If one of these requirements does not hold then the caller is in big troubles.

Note that slength name is a bit misleading.

Posted 26-May-12 3:08am

CPallini

Comments

Chuck O'Toole 26-May-12 9:21am

That covers it nicely +5

CPallini 27-May-12 13:24pm

Thank you.

nv3 26-May-12 9:57am

Thorough answer. Got my 5 although I think that homework should be done by the student ;-)

CPallini 27-May-12 13:24pm

Thank you.
(I'm not sure it is homework. It would be a poor example)

Code-o-mat 27-May-12 4:21am

My 5 also, completely agree with nv3.

CPallini 27-May-12 13:25pm

Thanks.