need help

[Regan Heath]

On Tue, 25 Apr 2006 15:51:03 +0800, Boris Wang <nano.kago at hotmail.com>  
wrote:
> "Regan Heath" <regan at netwin.co.nz>
> ??????:ops8jx4rqc23k2f5 at nrage.netwin.co.nz...
>> On Tue, 25 Apr 2006 13:55:21 +0800, Boris Wang <nano.kago at hotmail.com>
>> wrote:
>>> You are right, the args array begin from index 0, but
>>>
>>>>   foreach( char[] arg; args[0 .. args.length] )
>>>
>>> This should not be right, it should be :
>>>     foreach( char[] arg; args[0 .. args.length - 1] )
>>
>> That is not true.
>>
>> In D, arrays are indexed from 0 and when slicing the start index is
>> inclusive and the end index is not. Meaning, for example that:
>>
>> args[0..2]
>>
>> is a slice of items 0, and 1, but _not_ 2. If you use args.length-1 you
>> will _not_ include the last item of the array in the slice. If you want
>> the whole array then the end index must be the array length (AKA the  
>> index
>> of the item past the end of the array)
>>
>>> and more, when i run the followed code:
>>>
>>> import std.stdio;
>>>
>>> int main( char[][] args )
>>> {
>>>  foreach( char[] arg; args[0 .. args.length - 1 ] )
>>>  {
>>>   printf( "%s ", cast(char*)arg );
>>>  }
>>> }
>>>
>>> it even produce a assert:
>>>
>>> Error: AssertError Failure hello_my.d(10)
>>
>> The assert has nothing to do with the array slice and everything to do
>> with the missing return value in main. Try:
>>
>> import std.stdio;
>>
>> int main( char[][] args )
>> {
>>  foreach( char[] arg; args[0 .. args.length] )
>>  {
>>   printf( "%s ", cast(char*)arg );
>>  }
>>  return 0;
>> }
>>
>
> Why not a complie error, but a runtime error?

I believe the rationale is that it is not possible for the compiler to  
detect all possible situations with 100% certainty. I suspect Walter came  
to that conclusion adding this sort of compile time detection to his  
C/C++ compiler.

Regan