Re: what exactly is string length?
On Friday, 2 April 2021 at 15:01:07 UTC, mw wrote: BTW, shall I log a writeln() improvement bug ? It's really confusing, e.g as debug print or logs. In my opinion this isn't a bug. The nulls are actually printed: ``` $> rdmd test.d | hd 61 62 63 00 00 00 36 0a 68 65 61 64 2d 61 62 63 |abc...6.head-abc| 0010 00 00 00 2d 74 61 69 6c 31 36 0a |...-tail16.| 001b ``` It's just, that you can't see them, because it's an invisible character. If you want to get `\0` for nulls, you could write ``` writefln!"%(%s%)"(only(t)); ``` With this, `t` is printed as a string literal: ``` "head-abc\0\0\0-tail" ```
Re: what exactly is string length?
On Friday, 2 April 2021 at 05:02:52 UTC, mw wrote: On Friday, 2 April 2021 at 04:54:07 UTC, Computermatronic wrote: On Friday, 2 April 2021 at 04:49:22 UTC, mw wrote: So you mean inside the writeln() call, the 0s are skipped? Well, if I use `string t` as filename, it will try to looking for a file called: "head-abc\0\0\0-tail" instead of just "head-abc-tail" ? or it's platform dependent? I would imagine that it's platform dependant, but given most platforms adhere to the C ABI, and C string are null terminated, you'd end up looking for a file called "head-abc". Ahh, I got what I see (from writeln) is not what get string here ;-) BTW, shall I log a writeln() improvement bug ? It's really confusing, e.g as debug print or logs. Output something like: "head-abc\0\0\0-tail" "head-abc...-tail" "head-abc???-tail" is more clear.
Re: what exactly is string length?
On Friday, 2 April 2021 at 05:39:26 UTC, mw wrote:
Finally, I'm using:
https://run.dlang.io/is/651lT6
string t = text("head-", s[].until('\0').array, "-tail");
FYI, you don't need the call to `.array` there--`text` accepts
input ranges.
Re: what exactly is string length?
On Friday, 2 April 2021 at 05:18:49 UTC, H. S. Teoh wrote:
On Fri, Apr 02, 2021 at 05:05:21AM +, mw via
Digitalmars-d-learn wrote: [...]
This is just an example, what if the exact length is not known
statically, is there a functions to trim the `\0`s?
What about `s.until('\0')`?
Example:
auto s = "abc\0\0\0def";
auto t = "blah" ~ s.until('\0').array ~ "boo";
Finally, I'm using:
https://run.dlang.io/is/651lT6
string t = text("head-", s[].until('\0').array, "-tail");
It works for both s = "abc" (with \0), and "abcdef" (full 6
chars, indexOf will return -1 for bad range index).
Thank everyone who helped.
Re: what exactly is string length?
On Friday, 2 April 2021 at 04:32:53 UTC, mw wrote:
https://run.dlang.io/is/B4jcno
---
import std;
import std.conv : text;
void main()
{
char[6] s;
s = "abc";
writeln(s, s.length); // abc6, ok it's the static array's
length
string t = text("head-", s, "-tail");
writeln(t, t.length); // head-abc-tail16, why?
}
---
Why the last output is 16 instead of 13, t's type is string
here.
Test this:
https://run.dlang.io/is/Cq4vjP
Re: what exactly is string length?
On 02/04/2021 6:10 PM, Computermatronic wrote:
On Friday, 2 April 2021 at 05:02:52 UTC, mw wrote:
Ahh, I got what I see (from writeln) is not what get string here ;-)
And I just tried:
string t = text("head-", strip(s), "-tail");
It's the same behavior.
So how can I trim the leading & trailing `\0` from the static char array?
strip only removes whitespace, not null characters. You'd have to do
something like
```d string t = cast(string)text("head-", s, "-tail").filter!`a !=
'\0'`().array;```
I would assume there would be a better way, but I haven't been able to
find a dedicated function for stripping null chars in std.
If you know it has null terminators you can use fromStringz.
But this is a case of you should store the length.
Re: what exactly is string length?
On Fri, Apr 02, 2021 at 05:05:21AM +, mw via Digitalmars-d-learn wrote:
[...]
> This is just an example, what if the exact length is not known
> statically, is there a functions to trim the `\0`s?
Another way, if you want to avoid the extra allocation, slice the static
array with .indexOf:
s[0 .. s.indexOf('\0')]
should give you the initial segment up to the first null.
T
--
Questions are the beginning of intelligence, but the fear of God is the
beginning of wisdom.
Re: what exactly is string length?
On Fri, Apr 02, 2021 at 05:05:21AM +, mw via Digitalmars-d-learn wrote:
[...]
> This is just an example, what if the exact length is not known
> statically, is there a functions to trim the `\0`s?
What about `s.until('\0')`?
Example:
auto s = "abc\0\0\0def";
auto t = "blah" ~ s.until('\0').array ~ "boo";
T
--
What do you call optometrist jokes? Vitreous humor.
Re: what exactly is string length?
On Friday, 2 April 2021 at 05:02:52 UTC, mw wrote:
Ahh, I got what I see (from writeln) is not what get string
here ;-)
And I just tried:
string t = text("head-", strip(s), "-tail");
It's the same behavior.
So how can I trim the leading & trailing `\0` from the static
char array?
strip only removes whitespace, not null characters. You'd have to
do something like
```d string t = cast(string)text("head-", s, "-tail").filter!`a
!= '\0'`().array;```
I would assume there would be a better way, but I haven't been
able to find a dedicated function for stripping null chars in std.
Re: what exactly is string length?
On Friday, 2 April 2021 at 05:01:27 UTC, rikki cattermole wrote:
On 02/04/2021 5:51 PM, mw wrote:
Then how can I construct `t`? to make this assertion true:
assert(t == "head-abc-tail"); // failed!
Slice it.
string t = text("head-", s[0 .. 3], "-tail");
http://ddili.org/ders/d.en/slices.html
This is just an example, what if the exact length is not known
statically, is there a functions to trim the `\0`s?
Re: what exactly is string length?
On 02/04/2021 5:51 PM, mw wrote:
Then how can I construct `t`? to make this assertion true:
assert(t == "head-abc-tail"); // failed!
Slice it.
string t = text("head-", s[0 .. 3], "-tail");
http://ddili.org/ders/d.en/slices.html
Re: what exactly is string length?
On Friday, 2 April 2021 at 04:54:07 UTC, Computermatronic wrote:
On Friday, 2 April 2021 at 04:49:22 UTC, mw wrote:
So you mean inside the writeln() call, the 0s are skipped?
Well, if I use `string t` as filename, it will try to looking
for a file called:
"head-abc\0\0\0-tail" instead of just "head-abc-tail" ?
or it's platform dependent?
I would imagine that it's platform dependant, but given most
platforms adhere to the C ABI, and C string are null
terminated, you'd end up looking for a file called "head-abc".
Ahh, I got what I see (from writeln) is not what get string here
;-)
And I just tried:
string t = text("head-", strip(s), "-tail");
It's the same behavior.
So how can I trim the leading & trailing `\0` from the static
char array?
Re: what exactly is string length?
On Fri, Apr 02, 2021 at 04:32:53AM +, mw via Digitalmars-d-learn wrote:
[...]
> ---
> import std;
> import std.conv : text;
>
>
> void main()
> {
> char[6] s;
> s = "abc";
> writeln(s, s.length); // abc6, ok it's the static array's length
>
> string t = text("head-", s, "-tail");
> writeln(t, t.length); // head-abc-tail16, why?
> }
> ---
>
> Why the last output is 16 instead of 13, t's type is string here.
Because `s` contains 6 chars, and you only assigned 3 of them, so there
are 3 trailing null bytes that are inserted before "-tail". Null bytes
don't print anything, so you don't see them when printed as a string,
but if you cast it to ubyte[], you will see them:
writefln("%(%02X %)", t);
// Prints: 68 65 61 64 2D 61 62 63 00 00 00 2D 74 61 69 6C
Remember, this is D, not C. Strings are not terminated by nulls, so
appending the static array will append all 6 chars, including the nulls.
T
--
Holding a grudge is like drinking poison and hoping the other person dies. --
seen on the 'Net
Re: what exactly is string length?
On Friday, 2 April 2021 at 04:49:22 UTC, mw wrote:
On Friday, 2 April 2021 at 04:43:48 UTC, rikki cattermole wrote:
On 02/04/2021 5:38 PM, mw wrote:
On Friday, 2 April 2021 at 04:36:01 UTC, rikki cattermole
wrote:
On 02/04/2021 5:32 PM, mw wrote:
---
import std;
import std.conv : text;
void main()
{
char[6] s;
s = "abc";
writeln(s, s.length); // abc6, ok it's the static
array's length
string t = text("head-", s, "-tail");
writeln(t, t.length); // head-abc-tail16, why?
assert(t[9] == '\0');
}
---
I don't get it, what do you mean by the assertion:
assert(t[9] == '\0');
t == "head-abc-tail"
Not all characters can be printed such as NULL.
[104, 101, 97, 100, 45, 97, 98, 99, 0, 0, 0, 45, 116, 97, 105,
108]
So you mean inside the writeln() call, the 0s are skipped?
Well, if I use `string t` as filename, it will try to looking
for a file called:
"head-abc\0\0\0-tail" instead of just "head-abc-tail" ?
or it's platform dependent?
Then how can I construct `t`? to make this assertion true:
assert(t == "head-abc-tail"); // failed!
Re: what exactly is string length?
On Friday, 2 April 2021 at 04:49:22 UTC, mw wrote: So you mean inside the writeln() call, the 0s are skipped? Well, if I use `string t` as filename, it will try to looking for a file called: "head-abc\0\0\0-tail" instead of just "head-abc-tail" ? or it's platform dependent? I would imagine that it's platform dependant, but given most platforms adhere to the C ABI, and C string are null terminated, you'd end up looking for a file called "head-abc".
Re: what exactly is string length?
On Friday, 2 April 2021 at 04:43:48 UTC, rikki cattermole wrote:
On 02/04/2021 5:38 PM, mw wrote:
On Friday, 2 April 2021 at 04:36:01 UTC, rikki cattermole
wrote:
On 02/04/2021 5:32 PM, mw wrote:
---
import std;
import std.conv : text;
void main()
{
char[6] s;
s = "abc";
writeln(s, s.length); // abc6, ok it's the static
array's length
string t = text("head-", s, "-tail");
writeln(t, t.length); // head-abc-tail16, why?
assert(t[9] == '\0');
}
---
I don't get it, what do you mean by the assertion:
assert(t[9] == '\0');
t == "head-abc-tail"
Not all characters can be printed such as NULL.
[104, 101, 97, 100, 45, 97, 98, 99, 0, 0, 0, 45, 116, 97, 105,
108]
So you mean inside the writeln() call, the 0s are skipped?
Well, if I use `string t` as filename, it will try to looking for
a file called:
"head-abc\0\0\0-tail" instead of just "head-abc-tail" ?
or it's platform dependent?
Re: what exactly is string length?
On Friday, 2 April 2021 at 04:38:37 UTC, mw wrote:
On Friday, 2 April 2021 at 04:36:01 UTC, rikki cattermole wrote:
I don't get it, what do you mean by the assertion:
assert(t[9] == '\0');
t == "head-abc-tail"
Just tried this:
https://run.dlang.io/is/SFU5p4
```
import std;
import std.conv : text;
void main()
{
char[6] s;
s = "abc";
writeln(s, s.length); // abc6, ok it's the static array's
length
string t = text("head-", s, "-tail");
writeln(t, t.length); // head-abc-tail16, why 16 instead of
13, t's type is string here
assert(t[9] == '\0'); // ok
assert(t == "head-abc-tail"); // failed!
}
```
I'm even more puzzled by the last 2 assertions behavior: t is
print out as "head-abc-tail".
Re: what exactly is string length?
On 02/04/2021 5:38 PM, mw wrote:
On Friday, 2 April 2021 at 04:36:01 UTC, rikki cattermole wrote:
On 02/04/2021 5:32 PM, mw wrote:
---
import std;
import std.conv : text;
void main()
{
char[6] s;
s = "abc";
writeln(s, s.length); // abc6, ok it's the static array's length
string t = text("head-", s, "-tail");
writeln(t, t.length); // head-abc-tail16, why?
assert(t[9] == '\0');
}
---
I don't get it, what do you mean by the assertion:
assert(t[9] == '\0');
t == "head-abc-tail"
Not all characters can be printed such as NULL.
[104, 101, 97, 100, 45, 97, 98, 99, 0, 0, 0, 45, 116, 97, 105, 108]
Re: what exactly is string length?
On Friday, 2 April 2021 at 04:36:01 UTC, rikki cattermole wrote:
On 02/04/2021 5:32 PM, mw wrote:
---
import std;
import std.conv : text;
void main()
{
char[6] s;
s = "abc";
writeln(s, s.length); // abc6, ok it's the static array's
length
string t = text("head-", s, "-tail");
writeln(t, t.length); // head-abc-tail16, why?
assert(t[9] == '\0');
}
---
I don't get it, what do you mean by the assertion:
assert(t[9] == '\0');
t == "head-abc-tail"
Re: what exactly is string length?
On 02/04/2021 5:32 PM, mw wrote:
---
import std;
import std.conv : text;
void main()
{
char[6] s;
s = "abc";
writeln(s, s.length); // abc6, ok it's the static array's length
string t = text("head-", s, "-tail");
writeln(t, t.length); // head-abc-tail16, why?
assert(t[9] == '\0');
}
---
what exactly is string length?
https://run.dlang.io/is/B4jcno
---
import std;
import std.conv : text;
void main()
{
char[6] s;
s = "abc";
writeln(s, s.length); // abc6, ok it's the static array's
length
string t = text("head-", s, "-tail");
writeln(t, t.length); // head-abc-tail16, why?
}
---
Why the last output is 16 instead of 13, t's type is string here.
