Mistake in calling std::stable_sort?

struct SimGenRequest {

    int wakeup_mfm_;
    double value_;

    bool operator < ( const SimGenRequest & r2 ) const 
        { return ( wakeup_mfm_ < r2.wakeup_mfm_ ) ; }

};

Use :

std::stable_sort ( all_requests_.begin ( ), all开发者_Python百科_requests_.end ( ) );

Works ( compiles ). But

struct SimGenRequest {

    int wakeup_mfm_;
    double value_;

};

bool CompareByWakeTime ( const SimGenRequest & r1, const SimGenRequest & r2 ) {
    return ( r1.wakeup_mfm_ < r2.wakeup_mfm_ ) ;
}

Use :

std::stable_sort ( all_requests_.begin ( ), all_requests_.end ( ), 
    CompareByWakeTime );

does not work. Any pointers ?

The following is more or less your code. It compiles, and produces the expected output. To further help you, we need more information as to what isn't working.

#include <algorithm>
#include <iostream>
#include <set>
#include <vector>

struct SimGenRequest {

    int wakeup_mfm_;
    double value_;

    SimGenRequest(int w, double v) :
        wakeup_mfm_(w),
        value_(v)
    { }
};

bool CompareByWakeTime ( const SimGenRequest & r1, const SimGenRequest & r2 ) {
    return ( r1.wakeup_mfm_ < r2.wakeup_mfm_ ) ;
}

int main()
{
    std::vector<SimGenRequest> all_requests_;

    all_requests_.push_back(SimGenRequest(3, 1));
    all_requests_.push_back(SimGenRequest(4, 3));
    all_requests_.push_back(SimGenRequest(3, 2));
    all_requests_.push_back(SimGenRequest(1, 4));

    std::stable_sort(all_requests_.begin(), all_requests_.end(), CompareByWakeTime);

    for(std::vector<SimGenRequest>::const_iterator i = all_requests_.begin();
        i != all_requests_.end();
        ++i)
    {
        std::cout << '(' << i->wakeup_mfm_ << ", " << i->value_ << ')' << std::endl;
    }
    return 0;
}

STL uses onle operator less overloading. Otherwise you can specify any boolean functor for the sort, but you have to input it at the stable_sort call.