Initialising arrays

[bitvast]

In C, you can do this:


int myArray[5] = {1,2,3,4,5};

And I believe something similar can be done in some versions of BASIC. It would be nice to have a quick and simple way of initialising small arrays in BaCon without having to write a loop or do

myArray[0] = 1
myArray[1] = 2
etc.

Is this a good idea for a new feature? Since you can already do it in C I don't suppose it would be too hard to implement, but I've no idea really. What do you think, Peter?

p.s. Not sure if you can initialise multidimensional arrays in C like this:


int myArray[3][3] = {{1,2,3},{4,5,6},{7,8,9}}

If so, it would be nice to be able to do it in BaCon too.

[vovchik]

Dear bitvast,

This has always been possible in BaCon:


DECLARE adje$[] = { "autumn", "hidden", "bitter", "misty", "silent", "empty", "dry", "dark", "summer", "icy", \
"delicate", "quiet", "white", "cool", "spring", "winter", "patient", "twilight", "dawn", "crimson", \
"wispy", "weathered", "blue", "billowing", "broken", "cold", "damp", "falling", "frosty", "green", \
"long", "late", "lingering", "bold", "little", "morning", "muddy", "old", "red", "rough", \
"still", "small", "sparkling", "throbbing", "shy", "wandering", "withered", "wild", "black", "young", \
"holy", "solitary", "fragrant", "aged", "snowy", "proud", "floral", "restless", "divine", "polished", \
"ancient", "purple", "lively", "nameless" }


and you can get the size back with:


DEF FN bound(x) = SIZEOF(x)/SIZEOF(STRING)
x = bound(adje$)


I haven't tried this with multiple dimensions, but have a go...

With kind regards,
vovchik

[bitvast]

Hey vovchik, thanks. Multidimensions don't seem to work, although maybe I have the syntax wrong.

[Pjot]

Folks,

Multidimensional initialization always worked, see my example from 2010 here.

Another example:

DECLARE two_dim[3][3] = { { 1, 1}, {2, 2}, {3, 3} } TYPE int

PRINT two_dim[0][1]
PRINT two_dim[1][1]
PRINT two_dim[2][1]


HTH
Peter

[vovchik]

Thanks, Peter!

[bitvast]

Thanks Peter.

Just playing around, if you dimension the array to a number greater than the number of elements initialised, the remaining elements are zero-


DECLARE dim[10] = {1,2} TYPE int
PRINT dim[1]
PRINT dim[5]

Gives 2 and 0. But if you try to access an element beyond the dimension you still get zero-


DECLARE dim[10] = {1,2} TYPE int
PRINT dim[99]
I thought this would have generated an error.

Also, am I right in thinking that you cannot use OPTION BASE 1 with multiple dimensions? I get an error using it.

[Pjot]

Hi bitvast,

if you dimension the array to a number greater than the number of elements initialized, the remaining elements are zero

This is pure luck - it depends on the type of system, compiler, memory management etc.

Like mentioned in the manual, BaCon is a lazy converter - it simply passes your commands to C and it is handled there.

But if you try to access an element beyond the dimension you still get zero

Similarly, this has to do with the way your system allocates space on the stack. It is pure luck that you can refer to an element behind the allocated range, though a memory detection program like valgrind will issue a warning for this.

Also, am I right in thinking that you cannot use OPTION BASE 1 with multiple dimensions? I get an error using it.

The OPTION BASE currently is implemented for either one-dimensional arrays, or for multi-dimensional arrays but without initialization. This is a heritage from the past where the array parsing was handled differently. I will look into it again to see if this can be changed.

HTH,
Peter

[bitvast]

Message understood. So the moral is: don't play fast and loose with initializing arrays.

Thanks again, Peter.

[bigbass]

Here is a conversion table from C to BaCon

It has some documented things and undocumented discoveries
we made along the way and have some more that will be added soon


sourceforge.net/p/baconproto/wiki/C%20to%20BaCon/

Joe

[vovchik]

Dear Joe,

Thanks...It's a useful table.

With kind regards,
vovchik