March 21, 2005 Playing const char[]s into an Array? | |
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<code>
// Hardcoded section names!
const char[9] cfg_GENERAL = "[General]";
const char[9] cfg_WEAPONS = "[Weapons]";
const char[10] cfg_SUICIDES = "[Suicides]";
const char[6] cfg_MISC = "[Misc]";
const char[5] cfg_END = "[end]";
const char[5][] cfg_Sections;
cfg_Sections[0] = cfg_GENERAL;
cfg_Sections[1] = cfg_WEAPONS;
cfg_Sections[2] = cfg_SUICIDES;
cfg_Sections[3] = cfg_MISC;
cfg_Sections[4] = cfg_END ;
</code>
As you can see I have defined several const chars. But I noted I need to place
them into an array as well, to let me run them in loops.
I was actually trying to do something like this:
char[][] cfg_Sections = { cfg_GENERAL, cfg_WEAPONS, cfg_SUICIDES, cfg_MISC,
cfg_END};
-> Error: a struct is not a valid initializer for a char[][]
but that does not work either.
Any ideas?
AEon
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March 21, 2005 Re: Playing const char[]s into an Array? | |
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Posted in reply to AEon | Hi,
Array initialisers need to be specified in square brackets:
char[][] cfg_Sections = [ cfg_GENERAL, cfg_WEAPONS, cfg_SUICIDES,
cfg_MISC, cfg_END ];
However this won't compile as DMD complains about non-const casts - i.e.
it has to convert the static arrays (cfg_GENERAL etc) to dynamic arrays in
the array initialiser. Changing the constants to dynamic arrays works
though:
#import std.stdio;#
#const char[]cfg_GENERAL= "[General]";
#const char[]cfg_WEAPONS= "[Weapons]";
#const char[]cfg_SUICIDES= "[Suicides]";
#const char[]cfg_MISC= "[Misc]";
#const char[]cfg_END= "[end]";#
#char[][] cfg_Sections = [ cfg_GENERAL, cfg_WEAPONS, cfg_SUICIDES,
cfg_MISC, cfg_END ];#
#int main()
#{
# writefln( cfg_Sections[2] );
# return 0;
#}
This prints "[Suicides]" as expected.
On Mon, 21 Mar 2005 16:34:59 +0000 (UTC), AEon <AEon_member@pathlink.com>
wrote:
> char[][] cfg_Sections = { cfg_GENERAL, cfg_WEAPONS, cfg_SUICIDES,
> cfg_MISC,
> cfg_END};
--
Using Opera's revolutionary e-mail client: http://www.opera.com/m2/
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March 21, 2005 Re: Placing const char[]s into an Array? | |
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Posted in reply to Alex Stevenson | Alex Stevenson, >Array initialisers need to be specified in square brackets: > >char[][] cfg_Sections = [ cfg_GENERAL, cfg_WEAPONS, cfg_SUICIDES, >cfg_MISC, cfg_END ]; Right... I had been looking for initializers for char[], then found an example for int[], that tipped my off :) >However this won't compile as DMD complains about non-const casts - i.e. >it has to convert the static arrays (cfg_GENERAL etc) to dynamic arrays in >the array initialiser. Changing the constants to dynamic arrays works >though: > >#import std.stdio;# >#const char[]cfg_GENERAL= "[General]"; >#const char[]cfg_WEAPONS= "[Weapons]"; >#const char[]cfg_SUICIDES= "[Suicides]"; >#const char[]cfg_MISC= "[Misc]"; >#const char[]cfg_END= "[end]";# >#char[][] cfg_Sections = [ cfg_GENERAL, cfg_WEAPONS, cfg_SUICIDES, >cfg_MISC, cfg_END ];# >#int main() >#{ ># writefln( cfg_Sections[2] ); ># return 0; >#} > >This prints "[Suicides]" as expected. Yep, works like a charm. I only started using "const char[6]" etc. because these are the equivalent to the #define commands it used to use in ANSI C. Does the const in "const char[]cfg_END" actually mean anything. Since we are using a dynamic array? Some solutions I had come up with: // Will not work outside of a function though! char[][] cfg_Sections; cfg_Sections ~= cfg_GENERAL; cfg_Sections ~= cfg_WEAPONS; cfg_Sections ~= cfg_SUICIDES; cfg_Sections ~= cfg_MISC; cfg_Sections ~= cfg_END; a more brute force method would have been: char[][] cfg_Sections = [ "[General]", "[Weapons]", "[Suicides]", "[Misc]", "[end]" ]; AEon |
March 21, 2005 Re: Placing const char[]s into an Array? | |
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Posted in reply to AEon | On Mon, 21 Mar 2005 17:25:28 +0000 (UTC), AEon <AEon_member@pathlink.com> wrote: > Alex Stevenson, > > <<SNIP>> > > Does the const in "const char[]cfg_END" actually mean anything. Since we > are > using a dynamic array? It means the reference is constant: cfg_END = cfg_SUICIDES; cfg_END.length = 5; both of these produce 'not an lvalue' errors from the compiler. cfg_SUICIDES[2] = 'A'; compiles and runs under windows, but may crash under linux as the program is changing a value in the data segment of the program (where constants are stored). > > > Some solutions I had come up with: > > // Will not work outside of a function though! > char[][] cfg_Sections; > cfg_Sections ~= cfg_GENERAL; > cfg_Sections ~= cfg_WEAPONS; > cfg_Sections ~= cfg_SUICIDES; > cfg_Sections ~= cfg_MISC; > cfg_Sections ~= cfg_END; If you want this to be guaranteed to run, you could put it in a module constructor: #char[][] cfg_Sections; # #static this() #{ # cfg_Sections ~= cfg_GENERAL; # cfg_Sections ~= cfg_WEAPONS; # cfg_Sections ~= cfg_SUICIDES; # cfg_Sections ~= cfg_MISC; # cfg_Sections ~= cfg_END; #} regards, Alex |
March 21, 2005 Re: Placing const char[]s into an Array? | |
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Posted in reply to Alex Stevenson | If it helps, here is a shim I rolled to help deal with array initalization:
private import std.string;
template makeArray(T){
T[] makeArray(...){
T[] result;
for(uint i=0; i<_arguments.length; i++){
if(_arguments[i] == typeid(T)){
result ~= *cast(T*)_argptr;
_argptr += T.sizeof;
}
else throw new Exception(format("(makeArray) element %d is not of type
%s.",toString(i+1),typeid(T).toString()));
}
return result;
}
}
It's not as pretty as the static array initalization syntax (using []) but it
gets the job done:
array = makeArray!(char[])("one", "two", "three", "four");
It'll take as many arguments as you can throw at it.
- EricAnderton at yahoo
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March 21, 2005 Re: Placing const char[]s into an Array? | |
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Posted in reply to pragma | In article <d1n9gj$lea$1@digitaldaemon.com>, pragma says... > >If it helps, here is a shim I rolled to help deal with array initalization: > >private import std.string; > >template makeArray(T){ >T[] makeArray(...){ >T[] result; >for(uint i=0; i<_arguments.length; i++){ >if(_arguments[i] == typeid(T)){ >result ~= *cast(T*)_argptr; >_argptr += T.sizeof; >} >else throw new Exception(format("(makeArray) element %d is not of type >%s.",toString(i+1),typeid(T).toString())); >} >return result; >} >} > >It's not as pretty as the static array initalization syntax (using []) but it >gets the job done: Dude, until we get initialization, this is beautiful! Thanks! > >array = makeArray!(char[])("one", "two", "three", "four"); > >It'll take as many arguments as you can throw at it. > >- EricAnderton at yahoo |

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