I have the following class:

class Program
{
  char[] code;
  int fitness;
  int index;
  int sortval;
}

At one point, I am trying to change the length of the 'code' array, like so:

static void crossover(Program p, Program p1)
{
  int n;
  int i;
//...
  // memcpy(p.code + i, p1.code + j, n);
  char[] tmp = p.code[j..(j+n)];
  p.code.length = i + n;   // COMPILER ERROR
  p.code[i..(i+n)] = tmp[];
}

I don't understand why I get the error message: 'p.code.length is not an lvalue'...
I thought I could change the length of the array?

Thanks!
								-- Glenn Lewis

Glenn M. Lewis wrote:

[...]
> I get the error message: 'p.code.length is not an lvalue'...

Not confirmed. Your example complies okay on WIN98SE, dmd 0.81.

So long.

Glenn M. Lewis wrote:
> I have the following class:

I had to add some lines to get it to compile. (You didn't give us a compilable example to work with.)

Here's a complete example that does compile:



class Program
{
  char[] code;
  int fitness;
  int index;
  int sortval;
}



static void crossover(Program p, Program p1)
{
  int n;
  int i;

  int j;
//...
  // memcpy(p.code + i, p1.code + j, n);
  char[] tmp = p.code[j..(j+n)];
  p.code.length = i + n;   // COMPILER ERROR
  p.code[i..(i+n)] = tmp[];
}



void main()
{
  Program myP = new Program();
  Program myP1 = new Program();

  crossover(myP, myP1);
}


> 
> class Program
> {
>   char[] code;
>   int fitness;
>   int index;
>   int sortval;
> }
> 
> At one point, I am trying to change the length of the 'code' array, like so:
> 
> static void crossover(Program p, Program p1)
> {
>   int n;
>   int i;
> //...

I'm going to go out of a limb here and guess this is where the error is.

I'm going to go even farther out on a limb and guess you have something like this in there:  p.code.length++;

If so, you'll have to change it to:  p.code.length = p.code.length + 1;


If none of this helps, you might try posting a fuller example. I can't find anything wrong with the code you've posted. If I could duplicate your error, I might be able to fumble around into a solution.

>   // memcpy(p.code + i, p1.code + j, n);
>   char[] tmp = p.code[j..(j+n)];
>   p.code.length = i + n;   // COMPILER ERROR
>   p.code[i..(i+n)] = tmp[];
> }
> 
> I don't understand why I get the error message: 'p.code.length is not an lvalue'...
> I thought I could change the length of the array?
> 
> Thanks!
>                                 -- Glenn Lewis


-- 
Justin
http://jcc_7.tripod.com/d/