Re: A question about structures

Francis Glassborow wrote:
> Pat wrote:
>> I'm in the process of teaching myself C++ (with the help of several 
>> good books) so I can develop some DLL's for another application.
>>
>> Looking through an example of one of these, there's a line that 
>> defines a structure as follows:
>>
>> struct ParameterDefinition primaryParams[]=
>> {
>>     {"x position =", kXpos, 1.0}
>>     {"y position =", kYpos, 2.0}
>>     {"z position =", kZpos, 0.0}
>> };
>>
>>
>> None of the books I've been reviewing define a structure in this way 
>> (at least so far).   So what is "ParameterDefinition"?  A pointer?  I 
>> assume it actually contains the code that defines this  structure 
>> type.  Is there a name for this way defining a structure?  I'd like to 
>> read more about that.
> 
> No, you have misunderstood. The above is NOT a definition of a struct. 
> struct ParameterDefinition is a type written in C form, C++ would just 
> use ParameterDefinition (it does not need the prefix 'struct' to tell 
> the compiler that the following is the name of a struct type.
> 
> Now given that 'struct ParameterDefinition' is just a long winded name 
> for a type we can read the whole declaration/definition as:
> 
> primaryParams is an array (size to be deduced from the provided 
> initialisers) of type ParameterDefinition which is to be initialised 
> with three sets of values.
> 
> Compare this with the simpler but similar
> 
> int array[] = {1, 2, 3};


Thanks.  You're right.  I removed the "struct" (so it just reads 
"ParameterDefinition primaryParams[]=") and it stilled compiled and ran 
fine.  So that now makes sense (except now I'm going have to sort out 
what's C vs C++ !)

The question now though is where is ParameterDefinition actually 
defined?  It's definition is not shown in the source file I'm working 
with.  I guess I need to start checking the files referenced in the
headers.

But as an academic exercise, I assume ParameterDefinition looks 
something like this?

struct ParameterDefinition
{
	char coordinateName[20];
         double units;
	double coordinateValue;
};



(BTW, there should have been commas after each structure element in my 
original example).