Question about array initialization

[poorchava]

I'm currently writing a program, that needs a two-dimensional array on float values. How do initialize a 2-dimensional array without specifying it's exact size?

[Courageous]

You can declare it without specifying its exact size, but you cannot "initialize" an array without doing so. For that, you'll need some other data structure. What are you trying to do?

[Ravatar]

int dimension1 = 100;
int dimension2 = 550;
float[,] myArray = (float[,])Array.CreateInstance(typeof(float), dimension1, dimension2);

[Sep102]

Or, put another way that isn't the slower way of doing it:

Int32 size1 = 250
    , size2 = 100;

Int32 [,] array = new Int32[size1, size2]

Note, that I'm not saying it's a bad way, just a slower way that doesn't take into account what the C# compiler intrinsically knows about.

Also, I'm not so sure that's what the OP wants. I'm thinking it's something along the lines of:

Int32 lowerSize = 100;
Int32 [,] array = new Int32[,size];

That is, leaving the upper bounds undetermined, which, as Courageous said, cannot be done using native arrays but can be done with other data structures.

There's something along the lines of what he's talking about in C++, but it doesn't really have to do with array initialization (still it's the first thing I thought of when reading his post):

void f(int a[][10])
{}

int main()
{
    int a[1][10];
    f(a);
}

But that's really just another way of saying "int (*a)[10]".

Of course, I could be wrong as well, just have to wait until they answer Courageous' question.

[noobie]

he is probably talking about pointers but as far as I can tell, you cant do it in any language. you cant initialize something if you dont know the size. you need to use dynamic arrays/data structures.

[poorchava]

it can be easily done on PHP (so says my friend- who's a PHP freak )

[Ravatar]

Originally Posted by Sep102

Or, put another way that isn't the slower way of doing it:

Int32 size1 = 250
    , size2 = 100;

Int32 [,] array = new Int32[size1, size2]

Note, that I'm not saying it's a bad way, just a slower way that doesn't take into account what the C# compiler intrinsically knows about.

Also, I'm not so sure that's what the OP wants. I'm thinking it's something along the lines of:

Int32 lowerSize = 100;
Int32 [,] array = new Int32[,size];

That is, leaving the upper bounds undetermined, which, as Courageous said, cannot be done using native arrays but can be done with other data structures.

There's something along the lines of what he's talking about in C++, but it doesn't really have to do with array initialization (still it's the first thing I thought of when reading his post):

void f(int a[][10])
{}

int main()
{
    int a[1][10];
    f(a);
}

But that's really just another way of saying "int (*a)[10]".

Of course, I could be wrong as well, just have to wait until they answer Courageous' question.

Yea.. for some reason I was under the impression you couldn't define array bounds at runtime. Guess I've been working in C++ too much recently.

[noobie]

however you could use pointers in C++ for that matter (arrays are basically pointers): int** myArray