guide me to make this code better or efficient

given this prototype code how could I improve this?

Code:

---

#include "geocoding.h"
int main()
{
        vector<vector<vector<SURFACEMODEL> > > radar = invgeocoding();
        dirgeocoding(radar);
        return 0;
}

#include "geocoding.h"
vector<vector<vector<SURFACEMODEL> > > invgeocoding()
{
        // read input parameters

    // memory allocations
    vector<vector<SURFACEMODEL> > dtmpixel(ny_dtm, vector<SURFACEMODEL>(nx_dtm));
    vector<vector<vector<SURFACEMODEL> > > radarpixel(ny_radar, vector<vector<SURFACEMODEL> >(nx_radar));

        // read SURFACEMODEL data binary file

        // copy relevant surface data to radar dimension matrix (smaller than surface)

        return radarpixel;
}


#include "geocoding.h"
void dirgeocoding(vector<vector<vector<SURFACEMODEL> > > radarpixel)
{
        //  interpolation of height data for each radarpixel
}

---

I am learning C++ by doing, I am used to prototyping / calculating with matlab but don't really have the grip on references and pointers in C. Considering my surface model could be hundreds of MB's should I free memory somewhere? Typically surface 2D vector (dtmpixel) should be much larger than radar 3D vector (radarpixel). In function dirgeocoding I need to calculate some values of class SURFACEMODEL. I would like to advance a little bit and don't waste too much unnecessary memory.
Best regards

You probably do not want to make a copy of a potentially huge vector of vectors of vectors, so change this:

Code:

---

void dirgeocoding(vector<vector<vector<SURFACEMODEL> > > radarpixel)

---

to:

Code:

---

void dirgeocoding(const vector<vector<vector<SURFACEMODEL> > >& radarpixel)

---

Note that invgeocoding() returns by value, but return value optimisation would alleviate this unnecessary copying problem.

You can use a reference. It functions as an alias, and often doesn't have to use a pointer.

Code:

---

typedef vector<vector<vector<SURFACEMODEL> > > big_t;
void initialize(big_t & ref);
int main()
{
    big_t radar;
    initialize(radar); //radar is not copied
}

void initialize(big_t & ref)
{
    //Do stuff to ref, which refers to the variable in main()
}

---

This way if you have one big object, you only need that one.

Is this what you were asking?

I tried that but I doesn't compile after I change that. I get:

D:\IG\program\geocoding\090117\dirgeocoding.cpp:14 : error: passing `const PIXEL' as `this' argument of `void PIXEL::printdata()' discards qualifiers

In function dirgeocoding I need to change some values of SURFACEMODEL and at the moment I just call radarpixel[y][x][n].printdata(); for testing which earlier worked to print the variables of the sought instance.
Any idea?

In that case you should remove the const qualifier. It also implies that your original code has a bug.

when I remove const I get:
Release\main.o:main.cpp:(.text+0x5ea): undefined reference to `dirgeocoding(std::vector<std::vector<std::vector< SURFACEMODEL , std::allocator<SURFACEMODEL > >, std::allocator<std::vector<SURFACEMODEL , std::allocator<SURFACEMODEL > > > >, std::allocator<std::vector<std::vector<SURFACEMODE L , std::allocator<SURFACEMODEL > >, std::allocator<std::vector<PIXEL, std::allocator<SURFACEMODEL

and sorry for the confusion, but I changed the name of SURFACEMODEL to PIXEL in previous post.
cheers

Rebuild the code and make sure that the function prototype is correct.

I tried that and thanks, but no go

Then show the current code?

Quote:

---

Originally Posted by larne

I tried that but I doesn't compile after I change that. I get:

D:\IG\program\geocoding\090117\dirgeocoding.cpp:14 : error: passing `const PIXEL' as `this' argument of `void PIXEL::printdata()' discards qualifiers

In function dirgeocoding I need to change some values of SURFACEMODEL and at the moment I just call radarpixel[y][x][n].printdata(); for testing which earlier worked to print the variables of the sought instance.
Any idea?

---

Does printdata() actually modify the pixel data? If not, then it should be declared const in the first place.
If it's is intended that printdata() should modify the data, then as Laserlight says, you should not call it with const reference. There are now two possibly correct options:

• If you intend for it to modify the actual data in the original vector of vectors, then you will need to pass it by reference, not copy it by calling by value as you are in the original code.
• If you actually modify the data in the vector of vector, and you do not want to modify the original data to be modified, you should make a copy, and call by value is one way to achieve that.

--
Mats

I changed my function dirgeocoding to

Code:

---

void dirgeocoding(const vector<vector<vector<SURFACEMODEL> > >& radarpixel)

---

as suggested by laserlight. I skipped const since I will want to calculate a value of SURFACEMODEL in function dirgeocoding. However i get a strange builderror like this

Code:

---

--------------------Configuration: main - Win32 Debug--------------------
Linking...
main.obj : error LNK2001: unresolved external symbol "void __cdecl dirgeocoding(class std::vector<class std::vector<class std::vector<class SURFACEMODEL,class std::allocator<class SURFACEMODEL> >,class std::allocator<class std::vector<class SURFACEMODEL,class std::alloc
ator<class SURFACEMODEL> > > >,class std::allocator<class std::vector<class std::vector<class SURFACEMODEL,class std::allocator<class SURFACEMODEL> >,class std::allocator<class std::vector<class SURFACEMODEL,class std::allocator<class SURFACEMODEL> > > > > >)" (?dirgeocoding@@YAXV?$v
ector@V?$vector@V?$vector@VSURFACEMODEL@@V?$allocator@VSURFACEMODEL@@@std@@@std@@V?$allocator@V?$vector@VSURFACEMODEL@@V?$allocator@VSURFACEMODEL@@@std@@@std@@@2@@std@@V?$allocator@V?$vector@V?$vector@VSURFACEMODEL@@V?$allocator@VSURFACEMODEL@@@std@@@std@@V?$allocator@V?$vector@VSURFACEMODEL@@V?$a
llocator@VSURFACEMODEL@@@std@@@std@@@2@@std@@@2@@std@@@Z)
Debug/main.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.

main.exe - 2 error(s), 0 warning(s)

---

I found the error, I had not changed the declaration of the function in header file. Thanks for all your help, and sorry for wasting your time with this last one =/
Cheers