Hallo,

what is the standard D way of appending a char to a char[]?
I've go a function expecting a char[]. How do I convert a char to a
char[] in a function call?

void xyz(char[] abc);
{
	char[] string = "My string";
	char c = '!';
	xyz(string ~ c);
}

Stephan

Stephan Wienczny wrote:

> Hallo,
>
> what is the standard D way of appending a char to a char[]?
> I've go a function expecting a char[]. How do I convert a char to a
> char[] in a function call?
>
> void xyz(char[] abc);
> {
>     char[] string = "My string";
>     char c = '!';
>     xyz(string ~ c);
> }
>
> Stephan
>
What about using an array?

ie
   xyz(string ~ "!");
or
   char [] c = "!";
   xyz(string ~ c);

-- 
-Anderson: http://badmama.com.au/~anderson/

J Anderson wrote:
> Stephan Wienczny wrote:
> 
>> Hallo,
>>
>> what is the standard D way of appending a char to a char[]?
>> I've go a function expecting a char[]. How do I convert a char to a
>> char[] in a function call?
>>
>> void xyz(char[] abc);
>> {
>>     char[] string = "My string";
>>     char c = '!';
>>     xyz(string ~ c);
>> }
>>
>> Stephan
>>
> What about using an array?
> 
> ie
>    xyz(string ~ "!");
> or
>    char [] c = "!";
>    xyz(string ~ c);
> 

and how can I convert a single char into a char[]
I've written a function trying to do that, but I get unexpected results

import std.stream;

	char[] Char2String(char c)
	{
		char[1] result = c;

		debug
		{
		stdout.write("Char2String result: "~result~" input: ");
		stdout.write(c);
		stdout.writeLine("");
		}
		return result;
	}

int main(char[][] argv)
{
	stdout.writeLine(Char2String('!'));
	stdout.writeLine("end.");
	return 0;
}

The debug output is correct but the result is not.

"Stephan Wienczny" <wienczny@web.de> wrote in message news:bus08a$1fg8$1@digitaldaemon.com...
> J Anderson wrote:
> > Stephan Wienczny wrote:
> >
> >> Hallo,
> >>
> >> what is the standard D way of appending a char to a char[]?
> >> I've go a function expecting a char[]. How do I convert a char to a
> >> char[] in a function call?
> >>
> >> void xyz(char[] abc);
> >> {
> >>     char[] string = "My string";
> >>     char c = '!';
> >>     xyz(string ~ c);
> >> }
> >>
> >> Stephan
> >>
> > What about using an array?
> >
> > ie
> >    xyz(string ~ "!");
> > or
> >    char [] c = "!";
> >    xyz(string ~ c);
> >
>
> and how can I convert a single char into a char[]
> I've written a function trying to do that, but I get unexpected results
>
> import std.stream;
>
> char[] Char2String(char c)
> {
> char[1] result = c;

'result' is a static array, not a dynamic array. Static array data lives on the stack (I thnk). Dynamic array data lives in the heap. Why didn't your original code work? If you really want a function to do it try something like

char[] Char2String(char c)
{
char[] result;
result ~= c;

[snip]

>
> debug
> {
> stdout.write("Char2String result: "~result~" input: ");
> stdout.write(c);
> stdout.writeLine("");
> }
> return result;
> }
>
> int main(char[][] argv)
> {
> stdout.writeLine(Char2String('!'));
> stdout.writeLine("end.");
> return 0;
> }
>
>
> The debug output is correct but the result is not.
> I would expect that it outputs:
>

Ben Hinkle wrote:
> 
> 
> 'result' is a static array, not a dynamic array. Static array data lives on
> the stack (I thnk). Dynamic array data lives in the heap. Why didn't your
> original code work? If you really want a function to do it try something
> like
> 
> char[] Char2String(char c)
> {
> char[] result;
> result ~= c;
> 
> [snip]
> 
> 

Shouldn't the compiler generate a copy?!?

Stephan Wienczny wrote:

> Ben Hinkle wrote:
>
>>
>>
>> 'result' is a static array, not a dynamic array. Static array data lives on
>> the stack (I thnk). Dynamic array data lives in the heap. Why didn't your
>> original code work? If you really want a function to do it try something
>> like
>>
>> char[] Char2String(char c)
>> {
>> char[] result;
>> result ~= c;
>>
>> [snip]
>>
>>
>
> Shouldn't the compiler generate a copy?!?
>

I agree, it should be simpler.

-- 
-Anderson: http://badmama.com.au/~anderson/

template TMakeArray(T) { T[] makeArray(T t ) { T[] r; r ~= t; return r; } }

char [] foo = TMakeArray!(char).makeArray('T') ~ "his is only a test";

Is usually what I do , I don't know how effecient it is :/.  I'm also not sure why making r "T[1] r;r[0] = t;" doesnt work , you can only append dynamic arrays ?

C

"Stephan Wienczny" <wienczny@web.de> wrote in message news:burtne$1ahk$1@digitaldaemon.com...
> Hallo,
>
> what is the standard D way of appending a char to a char[]?
> I've go a function expecting a char[]. How do I convert a char to a
> char[] in a function call?
>
> void xyz(char[] abc);
> {
> char[] string = "My string";
> char c = '!';
> xyz(string ~ c);
> }
>
> Stephan
>

"Stephan Wienczny" <wienczny@web.de> wrote in message news:bus3tj$1ktm$1@digitaldaemon.com...
> Ben Hinkle wrote:
> >
> >
> > 'result' is a static array, not a dynamic array. Static array data lives
on
> > the stack (I thnk). Dynamic array data lives in the heap. Why didn't
your
> > original code work? If you really want a function to do it try something like
> >
> > char[] Char2String(char c)
> > {
> > char[] result;
> > result ~= c;
> >
> > [snip]
> >
> >
>
> Shouldn't the compiler generate a copy?!?
>

It is like in C when you declare a "static array" and return a pointer to it. I could see arguments for either behavior - C compatibility or implicit copying. Consider also how assignment/casting works, though. If you write

char [] a;
char [10] b;
a = b;

then both a and b point to the same data. If returning a static array made a copy of the data then one could argue that the assignment a=b should also make a copy. Otherwise

char[] foo()
{
char[10] b;
return b;
}

would create a copy but

char[] foo()
{
char[10] b;
char[] a;
a = b;
return a;
}

wouldn't.

-Ben

Ben Hinkle wrote:
> "Stephan Wienczny" <wienczny@web.de> wrote in message
> news:bus3tj$1ktm$1@digitaldaemon.com...
> 
>>Ben Hinkle wrote:
>>
>>>
>>>'result' is a static array, not a dynamic array. Static array data lives
> 
> on
> 
>>>the stack (I thnk). Dynamic array data lives in the heap. Why didn't
> 
> your
> 
>>>original code work? If you really want a function to do it try something
>>>like
>>>
>>>char[] Char2String(char c)
>>>{
>>>char[] result;
>>>result ~= c;
>>>
>>>[snip]
>>>
>>>
>>
>>Shouldn't the compiler generate a copy?!?
>>
> 
> 
> It is like in C when you declare a "static array" and return a pointer to
> it. I could see arguments for either behavior - C compatibility or implicit
> copying. Consider also how assignment/casting works, though. If you write
> 
> char [] a;
> char [10] b;
> a = b;
> 
> then both a and b point to the same data. If returning a static array made a
> copy of the data then one could argue that the assignment a=b should also
> make a copy. Otherwise
> 
> char[] foo()
> {
> char[10] b;
> return b;
> }
> 
> would create a copy but
> 
> char[] foo()
> {
> char[10] b;
> char[] a;
> a = b;
> return a;
> }
> 
> wouldn't.
> 
> -Ben
> 
> 

The compiler should forbid to return static data as the result is undefined. Another way would be to only copy if used as return value.

C wrote:

>template TMakeArray(T) { T[] makeArray(T t ) { T[] r; r ~= t; return r; } }
>
>char [] foo = TMakeArray!(char).makeArray('T') ~ "his is only a test";
>
>Is usually what I do , I don't know how effecient it is :/.  I'm also not
>sure why making r "T[1] r;r[0] = t;" doesnt work , you can only append
>dynamic arrays ?
>
>C
>
>  
>
No, I think it's about returning static arrays because this works...

   char[1] result;
   result[0] = '!';      printf("%.*s", (string ~ result));

-- 
-Anderson: http://badmama.com.au/~anderson/