C++ checking two versions of functions

Question

I'm writing an exercise in C++, and I wrote a code that seems to me to be valid, but I don't know for sure, as I'm still a beginner, can someone check it and tell me if they are the same or not.

The solution code:

Point *PointArray::get( const int pos) {
    return pos >= 0 && pos < size ? points + pos : NULL;
}

and my code is:

Point* PointArray::get (const int position) {
    return &(data[position]);
}

I realize that in my code i have to check the conditions to check if to return a null pointer or not, but apart from that, is my version the same as points + pos

points & data are arrays of Point class, i named mine data, the solution named it points.

EDIT:

my code after i added the condition to it:

Point* PointArray::get (const int position) {
    return ((position >= 0 && position < size) ? &(data[position]) : NULL);
}

Besides the checking that pos >= 0, they are the same – David Z. Apr 22 '12 at 08:14 — David Z., Apr 22 '12 at 08:14

score 5 · Accepted Answer · edited May 23 '17 at 10:24

5

In a nutshell, they do the same thing. There are some differences though:

1) The solution code checks the array bounds. Your solution does not.

2) The solution uses pointer arithmetic and avoids an extra dereference/address-of operation (most compilers will optimize this for you). See Efficiency: arrays vs pointers.

edited May 23 '17 at 10:24

Community

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answered Apr 22 '12 at 08:16

David Z.

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Yeh, I editied my code to include the consitions. Thanks David – hakuna matata Apr 22 '12 at 08:18
Discussion of differences in 2, seems like modern compilers do optimize this out. http://stackoverflow.com/questions/2305770/efficiency-arrays-vs-pointers – David Z. Apr 22 '12 at 08:28
@David Z.: not relevant here, there one of the access is without the position shift. – Karoly Horvath Apr 22 '12 at 08:39

C++ checking two versions of functions

1 Answers1