c++ How to sort an array of structs

Question

I have an array of structs as you can see below.

struct valueCache
{
    bool valid;
    int startPc;
    int index;
    f32bit input[12];
    f32bit result[12];
};

static const int vcSize = 32;
static valueCache * vc = new valueCache[vcSize];

I want to sort this array in descending order by the index. So I tried this:

myClass.cpp

bool myClass::sortByIndex(const valueCache &lhs, const valueCache &rhs) { return lhs.index > rhs.index; }

bool myClass::sortArray(
{    
    std::sort(vc, vc + vcSize, sortByIndex);
}

myClass.h

class myClass
{
public:
    bool sortByIndex(const valueCache &lhs, const valueCache &rhs);
}

and i get this error

error: argument of type 
‘bool (gpu3d::myClass::)(const gpu3d::valueCache&, const gpu3d::valueCache&)’ does not match 
‘bool (gpu3d::myClass::*)(const gpu3d::valueCache&, const gpu3d::valueCache&)’

Any ideas how I can fix this?

Answer 1

Declare sortByIndex static, because you cannot pass non-static member function to std::sort.