CODEWITHSUNDEEP
c++arraysfunction
Angus
Angus

Reputation: 101

Passing multidimensional array to a function (c++)?

I've been trying to pass a multidimensional array, of an unknown size, to a function, and so far have had no luck, when the array is declared, its dimensions are variables:

double a[b][b];

As far as I can tell, I need to give the value of b when I declare the function, a can be unknown. I tried declaring b as a global variable, but it then says that it must be a constant.

ie:

int b;

double myfunction(array[][b])
{
}

int main()
{
int a;
double c;
double myarray[a][b];

c=myfunction(myarray);

return 0;
}

Is there any way get this to work?

Upvotes: 4

Views: 5064

Answers (4)

shotex
shotex

Reputation: 381

if you want to pass an array of unknown size you can declare an array in Heap like this

//Create your pointer
int **p;
//Assign first dimension
p = new int*[N];
//Assign second dimension
for(int i = 0; i < N; i++)
p[i] = new int[M];


 than you can declare a function like that: 
double myFunc (**array);

Upvotes: 1

Mr.Anubis
Mr.Anubis

Reputation: 5342

Pass by value :

double myfunction(double (*array)[b]) // you still need to tell b

Pass by ref :

double myfunction(int (&myarray)[a][b]); // you still need to tell a and b

Template way :

template<int a, int b> double myfunction(int (&myarray)[a][b]); // auto deduction

Upvotes: 4

Sean McCully
Sean McCully

Reputation: 1132

Perhaps reading some references on C++ and arrays would help,

http://en.cppreference.com/w/cpp/container/array

Upvotes: 1

Caesar
Caesar

Reputation: 9863

void procedure (int myarray[][3][4])

More on this here

Upvotes: -1

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