Question

Is there a way to pass ‘std::vector 2d’ as a pointer to ‘2d c array’ to a function.

I know you can pass std::vector 1d as a pointer to c array to some function.
for example,
function:

void foo(char* str); //requires the size of str to be 100 chars

std::vector<char> str_;
str_.resize(100);
foo(&str_[0]); //works

I’m wondering if it is possible for 2d vectors too like for
function

void foo(char** arr_2d);

and vector

std::vector<std::vector<char>> vector_2d;

I tried the following code but im getting some error related to heap corruption.

std::vector<std::vector<unsigned char>> vector_2d;
//assuming function expects the size of the vector to be 10x10  
vector_2d.resize(10);
for(int i=0;i<10;i++)
{
    vector_2d[i].resize(10);
}
foo(&vector_2d[0]);//error here

Answer 1

Here’s what you can do:

std::vector< std::vector<unsigned char> > vector_2d;
vector_2d.resize(10);
std::vector<unsigned char*> ptrs(vector_2d.size());
for(int i=0;i<10;i++)
{
    vector_2d[i].resize(10);
    ptrs[i] = &vector_2d[i][0];
}
foo(&ptrs[0]);