Is it possible to keep in container static array?

Question

I mean not keep pointer on array

std::vector<int*> vector;

but

std::vector<int[]> vector;

The problem is to keep such array in hash_map in order to compare not pointers when Insert there but when I try like this

std::hash_map<std::vector<BYTE>,std::string> xxx

I've got an error.

I have a hard time understanding your question, could you please rephrase it? Also note that a vector<int[]> is exactly the same thing as a vector<int*>. Did you maybe mean a vector<int[N]> (where N is a compile-time constant)? — sepp2k
– sepp2k, Commented Jan 9, 2012 at 22:51
The hash map in C++ is called unordered_map, and this works fine for me: std::unordered_map<std::vector<unsigned char>, std::string> — Benjamin Lindley
– Benjamin Lindley, Commented Jan 9, 2012 at 22:52
std::unordered_map<std::array<unsigned char, N>, std::string> is a possibility too, since the array is presumably statically-sized. — ildjarn
– ildjarn, Commented Jan 9, 2012 at 22:53
vector<int[3]> v; v.push_back({1, 2, 3}); This even makes GCC segfault :) — jrok
– jrok, Commented Jan 9, 2012 at 22:55
even with unordered_map I've got an error cannot convert from 'const std::vector<_Ty>' to 'size_t' — Артём Царионов
– Артём Царионов, Commented Jan 9, 2012 at 23:00

Jesse Good · Accepted Answer · 2012-01-09 23:27:37Z

2

You cant do std::vector<int[]> vector. You have to specify the size of the array for it to compile like this std::vector<int[5]> vector.

However, this is a bad idea because you can`t assign arrays to other arrays, etc. and you will get all kinds of errors when you try to use vector.

Instead, use vector<vector<int>> vector or in C++11 use vector<std::array<int, 5>> vector.

Also, I don't know what implementation of hash_map you are using so I dont know if the above solutions will work in your case. (Also, C++11 has unordered_map, so that might be preferable)

edited Jan 9, 2012 at 23:27

answered Jan 9, 2012 at 23:03

Jesse Good

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3 Comments

bitmask Over a year ago

What's C++11x? I know C++0x and C++11 :)

Артём Царионов Over a year ago

so put my vector into another vector?

Jesse Good Over a year ago

@Артём: Yes, that might work, but I don't know if the key for hash_map can be a container or not.

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