need help

[Boris Wang]

"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?





> However, you should be aware that using cast(char*) on a char[] and 
> passing the result to printf is dangerous. It's only working in this case 
> because the arguments are already null terminated, try this:
>
> import std.file;
> import std.string;
>
> int main( char[][] args )
> {
>  foreach( int i,char[] arg; splitlines(cast(char[])read("bug11.txt")) )
>  {
>      printf( "%d. %s\n", i,cast(char*)arg );
>  }
>  return 0;
> }
>
> (you'll need to create a bug11.txt containing a few lines of text)
>
> you should notice that the first printf shows the entire file, this is 
> because the splitlines array contains non-null terminated char[] arrays. 
> To safely pass them to functions expecting char* you should use toStringz, 
> eg.
>
> import std.file;
> import std.string;
>
> int main( char[][] args )
> {
>  foreach( int i,char[] arg; splitlines(cast(char[])read("bug11.txt")) )
>  {
>      printf( "%d. %s\n", i,toStringz(arg) );
>  }
>  return 0;
> }
>
> Regan