Why is the following not working? (DMD 0.71)

int main (char[][] args)
{
char[] s = "12345";

printf("%s --> ", (char *)s);
s = s[0 .. s.length-1]; // I want to strip the last char
printf("%s\n", (char *)s);
return 0;
}

It prints 12345 --> 12345

"kw" <kw_member@pathlink.com> a écrit dans le message news: bjgids$1hdv$1@digitaldaemon.com...

> s = s[0 .. s.length-1]; // I want to strip the last char

You are copying array in the same array as if you do :

s[0] = s[0];
s[1] = s[1];
...
s[s.length-1] = s[s.length-1];

Try it :

s.length--;

-- Nicolas Repiquet

kw wrote:
> Why is the following not working? (DMD 0.71)
> 
> int main (char[][] args)
> {
> char[] s = "12345";
> 
> printf("%s --> ", (char *)s);
> s = s[0 .. s.length-1]; // I want to strip the last char
> printf("%s\n", (char *)s);
> return 0;
> }
> 
> It prints 12345 --> 12345
> 
> 

try using
printf( "%.*s", s );   slices are not null terminated s[0..1] will still  printf %s as s[0] ... \0 (if you get my meaning)

"kw" <kw_member@pathlink.com> escreveu na mensagem news:bjgids$1hdv$1@digitaldaemon.com...
> Why is the following not working? (DMD 0.71)
>
> int main (char[][] args)
> {
> char[] s = "12345";
>
> printf("%s --> ", (char *)s);
> s = s[0 .. s.length-1]; // I want to strip the last char
> printf("%s\n", (char *)s);
> return 0;
> }
>
> It prints 12345 --> 12345


In D arrays are more than pointers, because they carry length information too. But String literals have a additional invisible \0 in the end. So when you say:


> printf("%s --> ", (char *)s);


You are treating the address/length pair that represents the array as a
"char*", so the length info is lost, but the invisible \0 at the end of
"12345" is used to terminate the string inside "printf".
When you slice the array, you just create a new address/length pair, so the
sliced variable


> s = s[0 .. s.length-1]; // I want to strip the last char


Points to the original "12345\0" array, when used as an array it'll give a reduced length. But when you cast it to "char*" the printf will find the \0 only after "5". So you either use "%.*s" instead (that handle "char[]" properly) or use the "toStringz" function from Phobos, that'll give a "char*" with the \0 at the end, so "toStringz(s[0 .. s.length-1])" will return a "char*" pointing a memory location containing "1234\0".

    Best regards,
    Daniel Yokomiso.

"Lord save me from your followers."


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Not working:
>> printf("%s\n", (char *)s);

>try using
>printf( "%.*s", s );   slices are not null terminated s[0..1] will still
>  printf %s as s[0] ... \0 (if you get my meaning)

Thanks! That worked.
I few warnings for things that are not very intuitive for C programmers would be
a nice addition.