In Patterns of Human Error, the slide 31 point that you should replce int with
size_t
why that consider an error ?

%u:

> In Patterns of Human Error, the slide 31 point that you should replce int with
> size_t
> why that consider an error ?

If T is a byte and the array size is 5 billion items, on 64 bit systems...? In the little find() function you compare it with the length, that's a size_t. Someone else will give you better answers.

Bye,
bearophile

void main()
{
    size_t val = int.max+1;
    int val2 = val;
    writeln(val2);
}

writes -2147483648

That should give you a hint.

size_t val1 = int.max+1;
int val2 = int.max+1;
writeln(val1); // 2147483648
writeln(val2); // -2147483648

very clear example

thanks you both

Actually my example was bad. What I wanted to say is that size_t will be 64bit on 64bit platforms while int will stay 32bit. Another difference is that size_t is unsigned. So it's bad to use int even if you're sure you're only going to compile only on 32bit platforms.

Here's the relevant definitions in object_.d:

version(X86_64)
{
    alias ulong size_t;
    alias long  ptrdiff_t;
    alias long  sizediff_t;
}
else
{
    alias uint  size_t;
    alias int   ptrdiff_t;
    alias int   sizediff_t;
}

And an example:
void main()
{
    size_t val = size_t.max;    // maximum unsigned 32bit number on
32bit platforms

    int val2 = val;
    writeln(val2);              // -1 on 32bit platforms, due to
unsigned -> signed conversion
}

Usually people type "int" because.. well it's used everywhere and it's easy to type. I never liked the "size_t" name, but it has become a de facto standard in other languages, so D uses that name as well. We've already had a discussion on changing its name but nothing came out of it.

Edit: I just saw you've already figured this out. :)

On 07/05/2011 18:09, %u wrote:
> In Patterns of Human Error, the slide 31 point that you should replce int with
> size_t
> why that consider an error ?

For those who aren't sure what this is on about:
http://www.slideshare.net/dcacm/patterns-of-human-error

But the short answer is because dim is a size_t, i needs to cover its range.

But....

<= should be = ?  Don't you mean < ?

And the use of a meaningless type alias gets at me.

Stewart.