如何根据结构的字段之一对结构指针列表进行排序？

Question

I have this code:

struct nod
{
    nod *vCap;
    int vCost;
    char vInfo;
}; 

list<nod*> vList;

for (int i = 9; i >= 0; i--) 
{
    nod *vTmp;
    vTmp->vCost=i;
    vTmp->vInfo='a';
    vList.push_back(vTmp);
}

How can I sort the list by the vCost value?

Answer 1

You'll need a custom comparator to compare the field you're interested in:

struct compare_nod_by_cost {
    bool operator()(nod const * a, nod const * b) {
        return a->vCost < b->vCost;
    }
};

Then you can provide it as the comparator for list::sort :

vList.sort(compare_nod_by_cost());

In C++11, you can compress this into a lambda:

vList.sort([](nod const * a, nod const * b) {return a->vCost < b->vCost;});

(Note that you almost certainly want to store objects, rather than pointers, in your list; in that case, change the comparator's pointer arguments to references).

Answer 2

使用lambda：

vList.sort([](const nod * a, const nod * b ) { return a->vCost < b->vCost; });

Answer 3

If the normal or natural ordering for a nod is by cost, then you might want to define its operator< to do that:

struct nod{
    nod*vCap; 
    int vCost;
    char vInfo;

    bool operator<(nod const &other)  { return vCost < other.vCost; }
};

Then, of course, you almost certainly want to create a list<nod> instead of a list<nod*> . Having done that, sorting items in a list will just be vList.sort(); .

Just FWIW, you also need to fix a typo in your definition of nod (you have a comma instead of a semicolon between the definitions of vCost and vInfo .