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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 |
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/ |
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 |
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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