If I define a struct like below
typedef struct Coder {
float **data;
};
For my convenience, I also define a pointer to this struct
typedef Coder *AUTO;
and then I have to initial it by calling
AUTO myInstance = new Coder;
My problem appear when I call
myInstance->data= NULL;
The VC 2010 told me that there was no type specifier. I don't understand what problem is here. Could you please help me?
If you are in C++, just do :
struct Coder
{
float **data;
};
typedef Coder *AUTO;
Also you have to be sure that the AUTO declaration is done after the declaration of your struct or you can forward-declare your struct.
Also, it is possible that NULL is undefined.
You can replace it by 0 or just look at the link I just gave you.
Here is a live example.
EDIT : The code you gave us cannot work :
#include <tchar.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <conio.h>
#include <iostream>
struct Coder {
float **data; // 2-D matrix
};
typedef Coder *AUTO;
AUTO myFeatures = new Coder;
myFeatures->data = NULL; // Forbidden
int main (){
myFeatures->data = new float *[2];
myFeatures->data[0] = new float [2];
}
You can only have declaration in namespace scope, not expression like that.
In §7.3.1/1 of the standard :
namespace-body:
declaration-seqopt
which says the namespace-body can optionally contain only declaration.
This code will work :
// Your includes
struct Coder {
Coder() : data(NULL) {} // Constructor who initialize data to NULL
// via the member-initialization-list
float **data; // 2-D matrix
};
typedef Coder *AUTO;
AUTO myFeatures = new Coder; // Do you want to keep it in global ??
// It's not a really good design
int main (){
// You should put your declaration here.
// myFeatures->data = NULL; useless now
myFeatures->data = new float *[2];
myFeatures->data[0] = new float [2];
}
myInstance = new Coder; that this is, in fact, C++ (the tag helps as well). And regardless, I don't believe that is the Op's issue.
struct Coder and the typedef for AUTO are even in the same file. Thus the reason for my answer.In C typedef:
typedef int mango;
Now your mango represent "int" datatype.
user defined struct syntax:
struct mystruct;
use typedef:
typedef struct mystruct newtype;
Now newtype represent your struct mystruct.
Your the typedef name is missing,
typedef struct Coder {
float **data;
}Coder ;
typedef struct Coder {
float **data;
}Coder;
will be ok.
typedefdoesn't have a name. Also, what's convenient about theAUTOtypedef? It just looks ugly and obfuscating to me.typedefon thestruct, to begin with? And whiletypedefing the pointer is already ugly and obfuscating, giving it a completely unrelated name, and all caps at that?