compilation error ::vector ::iteratator - c++

Question

I encounter this error whenever I compile my prg..
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:5394:5: note: template<class _RAIter> void std::sort(_RAIter, _RAIter)
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:5430:5: note: void std::sort(_RAIter, _RAIter, _Compare) [with _RAIter = __gnu_cxx::__normal_iterator<PointTwoD*, std::vector<PointTwoD> >, _Compare = bool (MissionPlan::*)(PointTwoD&, PointTwoD&)]
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:5430:5: note: no known conversion for argument 3 from '<unresolved overloaded function type>' to 'bool (MissionPlan::*)(PointTwoD&, PointTwoD&)'
Below is actually my .cpp file..
bool MissionPlan::sortByCiv(const PointTwoD &t1, const PointTwoD &t2)
{
return t1.locationdata.getCivIndex() < t2.locationdata.getCivIndex();
}
void MissionPlan::topfives()
{
topfive.assign( point1.begin(), point1.end() );
sort(topfive.begin(), topfive.end(), sortByCiv);
for(int i=0; i < 5; i++)
{
topfive.at(i).displayPointdata();
}
}
missionplan.h
class MissionPlan
{
private:
int sizeofarray;
int sizeofarray2;
int xcordi;
int ycordi;
LocationData locationdata;
PointTwoD pointtwoD;
//MissionPlan missionplan;
public:
MissionPlan();
MissionPlan(int, int, float);
int getx();
int gety();
float civnum;
float getciv();
void stats();
void storedata(int, int, float);
void test();
void displayall();
void compute();
void topfives();
static bool sortByCiv(const PointTwoD &t1, const PointTwoD &t2);
};
My programme will compile and run smoothly when I remove this line from my code "sort(topfive.begin(), topfive.end(), sortByCiv);"
so is there a problem with that line of code or there other thing that is affecting it?
this is the error msg is get when i start compiling after I made sortByCiv statc and change the function para to a const..
In file included from c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/algorithm:63:0,
from ..\src\/MissionPlan.h:9,
from ..\src\MissionPlanImp.cpp:3:
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h: In function '_RandomAccessIterator std::__unguarded_partition(_RandomAccessIterator, _RandomAccessIterator, const _Tp&, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<PointTwoD*, std::vector<PointTwoD> >, _Tp = PointTwoD, _Compare = bool (*)(PointTwoD&, PointTwoD&)]':
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:2265:78: instantiated from '_RandomAccessIterator std::__unguarded_partition_pivot(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<PointTwoD*, std::vector<PointTwoD> >, _Compare = bool (*)(PointTwoD&, PointTwoD&)]'
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:2306:62: instantiated from 'void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<PointTwoD*, std::vector<PointTwoD> >, _Size = int, _Compare = bool (*)(PointTwoD&, PointTwoD&)]'
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:5445:4: instantiated from 'void std::sort(_RAIter, _RAIter, _Compare) [with _RAIter = __gnu_cxx::__normal_iterator<PointTwoD*, std::vector<PointTwoD> >, _Compare = bool (*)(PointTwoD&, PointTwoD&)]'
..\src\MissionPlanImp.cpp:140:48: instantiated from here
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:2233:4: error: invalid initialization of reference of type 'PointTwoD&' from expression of type 'const PointTwoD'
c:\mingw\bin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:2236:4: error: invalid initialization of reference of type 'PointTwoD&' from expression of type 'const PointTwoD'
now finally the programme gets to run on command prompt but it gets terminate with the following error msg..
"terminate called after throwing an instance of 'std::out_of_range' what(): vecotr::_M_range_check"
Thanks guys I got it up and running, thanks and appreciate for all ur helps..

Answer 1

The issue here is that sortByCiv is a member function, which can only be invoked relative to some receiver object (i.e. myObject.sortByCiv(...) versus sortByCiv(...). The std::sort function expects you to provide as a parameter some function that can be called as a free function with two arguments that will then produce a value.
To fix this, make sortByCiv static. This makes it no longer have a receiver object and should resolve your issue.
Hope this helps!

Answer 2

sortByCiv is a member function and it needs special treatment; for instance, you cant cast it to function pointer type, as it has an implicit (third) this-parameter.
And in your case, you don't need to. Just move the sortByCiv(..) out of the class declaration(or make it static), as it doesn't use this parameter:
bool sortByCiv(const PointTwoD &t1, const PointTwoD &t2)
{
return t1.locationdata.getCivIndex() < t2.locationdata.getCivIndex();
}