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Create variable number of vectors in C ++

I can create a 2D-array of size n*m

, running: vector< vector< int > > foo(n, vector< int > (m))

.

Suppose I am assigned a variable number of values ​​at runtime, for example v_1, v_2, v_3, ..., v_k

and want to create the following:

vector< vector< ... vector< int > ... > > foo(v_1, vector< ... > (v_2, vector< ... > ..));

In other words, create a multidimensional array of size v_1* v_2 * v_3 ... *v_k

. How can i do this? Is it possible?

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2 answers


You cannot do this - the data type must be set at compile time. However, it is quite practical to use a single array with the correct count of all elements and create a mapping so that your boolean is [i1][i2][...]

found with a name [i1*v2*v3...vk + i2*v3..vk + ...]

.



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You need someone boost::variant

who can handle this. You can create a recursive_wrapper that allows you to nest content arbitrarily. There are other approaches, such as one large flat array, or you can use inheritance and dynamic allocation, but they take quite a lot of hassle.



typedef boost::variant<
    int,
    std::vector<boost::recursive_variant_>
> variant;

int main() {
    std::vector<variant> var; // Assume at least 1 dimension
}
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