Equivalent to table-driven code

[Richard Drysdall]

Hi.

In C/C++, I'm used to using a table-driven approach for some problems to
avoid large case statements. For example (off the top of my head, may
contain syntax errors and error checking excluded):

typedef struct
{
const char *name;
unsigned int id;

} ANIMALMAPPING;

static ANIMALMAPPING animalIdMapping [] =
{
{"frog", 174},
{"cow", 206},
{"bird", 92}
};

int GetAnimalIdFrom Name (const char *animalName)
{
for (int animal = 0; animal < ARRAYSIZE (animalIdMappin g); animal++)
if (stricmp (animalName, animalIdMapping [animal].name) == 0)
etc...
}

In C#, I seem to have trouble defining the animalIdMapping array - I've got:

private AnimalEffectMap ping [] animalEffectMap ping
= new AnimalEffectMap ping [3]
{
{"frog", 174},
{"cow", 206},
{"bird", 92}
};

but I get the following compile error:

error CS0623: Array initializers can only be used in a variable or field
initializer. Try using a new expression instead.

But when I try putting 'new AnimalEffectMap ping' in front of each line
in the table, the compiler thinks I'm trying to make an array out of
each line.

What do I need to change to get this working, and does C#/.Net offer a
better approach to solving this kind of problem than table-driven code?

Thanks.
--
Remove the blah's from my email address to reply.

[Jon Skeet [C# MVP]]

Richard Drysdall <dr************ **@fastmail.fmw rote:

In C#, I seem to have trouble defining the animalIdMapping array - I've got:

private AnimalEffectMap ping [] animalEffectMap ping
= new AnimalEffectMap ping [3]
{
{"frog", 174},
{"cow", 206},
{"bird", 92}
};

but I get the following compile error:

error CS0623: Array initializers can only be used in a variable or field
initializer. Try using a new expression instead.

You need to change each of the lines inside the array to something
like:

new AnimalEffectMap ping ("frog", 174),

Note the round brackets instead of braces. You're calling a constructor
- there's no equivalent of the sort of "automatic" struct
initialization in C.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

Jon Skeet [C# MVP] wrote:

Richard Drysdall <dr************ **@fastmail.fmw rote:

>In C#, I seem to have trouble defining the animalIdMapping array - I've got:

private AnimalEffectMap ping [] animalEffectMap ping
= new AnimalEffectMap ping [3]
{
{"frog", 174},
{"cow", 206},
{"bird", 92}
};

but I get the following compile error:

error CS0623: Array initializers can only be used in a variable or field
initializer. Try using a new expression instead.

You need to change each of the lines inside the array to something
like:

new AnimalEffectMap ping ("frog", 174),

Note the round brackets instead of braces. You're calling a constructor
- there's no equivalent of the sort of "automatic" struct
initialization in C.

Additionally, you might to look into the HashTable or Dictionary<>
classes, that offer far quicker searching than looping through all the
elements.

--
Göran Andersson
_____
http://www.guffa.com