invalid use of array with unspecified bounds.. why?

I have no idea what the problem is...
It is giving me this error: invalid use of array with unspecified
bounds

How can I fix it. Thanks.


#include <stdio.h>

// Prototype
void copy_arr(double a[][], double b[][], int size, int size2);

int main()
{
double source[5][5] = {
{1.1, 1.2, 1.3, 1.4, 1.5},
{2.1, 2.2, 2.3, 2.4, 2.6},
{3.1, 3.2, 3.3, 3.4, 3.5},
{4.1, 4.2, 4.3, 4.4, 4.5},
{5.1, 5.2, 5.3, 5.4, 5.5}
};

double target3[5][5];
int i;
int j;


copy_arr(source, target3, 5, 5);

printf("Array Copy\n");

for (i=0; i < 5; i++)
{
printf("\n");
for (j=0; j < 5; j++)
{
printf("%2.1f ", target3[i][j]);

}

}

printf("\n\n");
system("pause");
return 0;
}

void copy_arr(double a[][], double b[][], int size, int size2)
{
int i, j;
for (i = 0; i < size; i++)
for (j = 0; j < size2; j++)
**error is here ==> b[i][j] = a[i][j]; <== error is here**

}

re: invalid use of array with unspecified bounds.. why?

Andrew Joros (ezze16@gmail.com) wrote:[color=blue]
> I have no idea what the problem is...
> It is giving me this error: invalid use of array with unspecified
> bounds
> void copy_arr(double a[][], double b[][], int size, int size2);[/color]

you can't use [][] to specify function parameters. using double **
will accomplish the same thing and compile.

re: invalid use of array with unspecified bounds.. why?

"tedu" <tu@zeitbombe.org> writes:[color=blue]
> Andrew Joros (ezze16@gmail.com) wrote:[color=green]
>> I have no idea what the problem is...
>> It is giving me this error: invalid use of array with unspecified
>> bounds
>> void copy_arr(double a[][], double b[][], int size, int size2);[/color]
>
> you can't use [][] to specify function parameters.[/color]

Right.
[color=blue]
> using double ** will accomplish the same thing and compile.[/color]

No, it won't, at least not without changing the call as well as
the function.

Here's a snippet of the OP's code:

void copy_arr(double a[][], double b[][], int size, int size2);

int main()
{
double source[5][5] = {
[...]
};

double target3[5][5];
[...]
copy_arr(source, target3, 5, 5);
[...]

If you change the parameters to double**, the arguments have to be
pointers to pointers to double (possibly something that decays to that
type). source is a 2-dimensional array; the name decays to a pointer
to array of 5 doubles, not to a pointer to pointer.

--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

re: invalid use of array with unspecified bounds.. why?

Andrew Joros (ezze16@gmail.com) wrote:[color=blue]
> I have no idea what the problem is...
> It is giving me this error: invalid use of array with unspecified
> bounds[/color]

[...]
[color=blue]
> void copy_arr(double a[][], double b[][], int size, int size2)
> {
> int i, j;
> for (i = 0; i < size; i++)
> for (j = 0; j < size2; j++)
> **error is here ==> b[i][j] = a[i][j]; <== error is here**
>
> }[/color]

The compiler needs to know how big each element of the array is. Try:

void copy_arr(int size, int size2, double a[][size2], double b[][size2])
{
/* ... */
}

This will only work if your compiler supports variable-sized arrays,
which were added to the C standard in 1999.

Without variable-sized arrays, there is simply no way to pass an array
of arrays of arbitrary size to a function. You would need to change to a
different data structure, such as an array of pointers.

--
Simon.

re: invalid use of array with unspecified bounds.. why?

"Simon Biber" <news@ralmin.cc> wrote in message
news:43603199$0$28782$afc38c87@news.optusnet.com.a u...[color=blue]
> Andrew Joros (ezze16@gmail.com) wrote:[color=green]
>> I have no idea what the problem is...[/color][/color]
<SNIP>>[color=blue]
> The compiler needs to know how big each element of the array is. Try:
>
> void copy_arr(int size, int size2, double a[][size2], double b[][size2])
> {
> /* ... */
> }
>
> This will only work if your compiler supports variable-sized arrays, which
> were added to the C standard in 1999.
>
> Without variable-sized arrays, there is simply no way to pass an array of
> arrays of arbitrary size to a function. You would need to change to a
> different data structure, such as an array of pointers.[/color]

The standard says than an array is converted to a pointer, so it is possible
to pass an array to a function. You don't need variable sized arrays, but
you have to tell the compier how big the second dimension is:

void copy_arr(int size, int size2, double a[][5], double b[][5])
{....

wil work fine, even on older compilers. The arguments ar converted to type
double (*)[5]
as part of the ususal unary conversions, the type means 'a pointer to an
array of 5 doubles'

Now, the code will not produce a 'unspecified bounds error, becuase the size
of the object pointed to by the argument is known. (In the case of double
(*)[] it is not, accessing the second element (array) is not possible in
that case)
Ofcource, it is better to make the dimensions of the array a define, or make
a new type with a typedef.

DickB

re: invalid use of array with unspecified bounds.. why?

In article <1130370608.652046.219160@g49g2000cwa.googlegroups .com>,
"Andrew Joros (ezze16@gmail.com)" <ezze16@gmail.com> wrote:
[color=blue]
> // Prototype
> void copy_arr(double a[][], double b[][], int size, int size2);
>}[/color]

You may have other problems, but size and size2 are never assigned.

leo

--
<http://web0.greatbasin.net/~leo/>

re: invalid use of array with unspecified bounds.. why?

Dick de Boer wrote:[color=blue]
> "Simon Biber" <news@ralmin.cc> wrote in message
> news:43603199$0$28782$afc38c87@news.optusnet.com.a u...
>[color=green]
>>Andrew Joros (ezze16@gmail.com) wrote:
>>[color=darkred]
>>>I have no idea what the problem is...[/color][/color]
>
> <SNIP>>
>[color=green]
>>The compiler needs to know how big each element of the array is. Try:
>>
>>void copy_arr(int size, int size2, double a[][size2], double b[][size2])
>>{
>> /* ... */
>>}
>>
>>This will only work if your compiler supports variable-sized arrays, which
>>were added to the C standard in 1999.
>>
>>Without variable-sized arrays, there is simply no way to pass an array of
>>arrays of arbitrary size to a function. You would need to change to a
>>different data structure, such as an array of pointers.[/color]
>
>
> The standard says than an array is converted to a pointer, so it is possible
> to pass an array to a function. You don't need variable sized arrays, but
> you have to tell the compier how big the second dimension is:[/color]

If you read the OP's code, you'll see that he is trying to write a
general function that will work with any two-dimensional array, where
the size is given as a parameter of the function.
[color=blue]
>
> void copy_arr(int size, int size2, double a[][5], double b[][5])
> {....[/color]

Of course this code will work fine on older compilers, but it will only
work with arrays where the second dimension is exactly five! There's no
point even having a size2 argument in your function, since it will
*only* compile when size2 is 5.

It's better not to produce a function that is not limited to work with
arrays of a particular dimension.

--
Simon.

re: invalid use of array with unspecified bounds.. why?

Leonard Blaisdell <leo@greatbasin.com> writes:[color=blue]
> In article <1130370608.652046.219160@g49g2000cwa.googlegroups .com>,
> "Andrew Joros (ezze16@gmail.com)" <ezze16@gmail.com> wrote:
>[color=green]
>> // Prototype
>> void copy_arr(double a[][], double b[][], int size, int size2);
>>}[/color]
>
> You may have other problems, but size and size2 are never assigned.[/color]

Yes they are. size and size2 are arguments to the copy_arr function,
and the one call to it in the original code (which you snipped) passes
the values 5 and 5 as the corresponding arguments.

--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.