c++ memcpy read memory

Question

I'm trying to use memcpy to read memory.

BYTE test[] = {0x01};
BYTE test2[] = {0x00};
memcpy (test, test2, sizeof(test));
if (test == test2){
    MessageBox::Show("Same");
}else{
    MessageBox::Show("Different");
}

Why the test and test2 always different?

Thanks for your help.

The memory addresses will always be different and that is what you are testing — Halfpint, Oct 03 '16 at 15:21
Prefer standard containers (e.g. [`std::vector`](http://en.cppreference.com/w/cpp/container/vector)) to arrays. Then comparisons like this will work. — Fred Larson, Oct 03 '16 at 15:23

score 3 · Accepted Answer · answered Oct 03 '16 at 15:21

3

You're comparing addresses of test and test2. Use memcmp instead.

Your code is equivalent to

if (&test[0] == &test2[0]){

Changing it to

if (memcmp(test, test2, sizeof(test)) == 0)

should work as you expected.

answered Oct 03 '16 at 15:21

krzaq

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score 0 · Answer 2 · answered Oct 03 '16 at 15:21

0

Because you are testing equality for the address of the array. Try using memcmp instead.

answered Oct 03 '16 at 15:21

Buddy

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score 0 · Answer 3 · answered Oct 03 '16 at 15:21

0

When the name of an array is used by itself it turns into a pointer, so you're comparing the addresses of the two arrays, not their contents.

answered Oct 03 '16 at 15:21

sfjac

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c++ memcpy read memory

3 Answers3