I have two structs, for example, first struct as key in QMultiMap
:
struct KeyStruct
{
int keydata1;
int keydata2;
int keydata3;
bool operator < ( const KeyStruct& o ) const
{
return keydata1 < o.keydata1 || keydata2 < o.keydata2 || keydata3 < o.keydata3;
}
};
And second struct as value:
struct ValueStruct
{
int valuedata1;
QString valuedata2;
};
I tried to use QMultiMap
like this:
multiMap.insert( keyStruct, valueStruct ); // in a loop
foreach( keyStruct, multiMap.keys()){
foreach( valueStruct, multiMap.values( keyStruct )){
// it never reaches this line
}
}
I'm shure in some cases I have multiple values per key, but can't even get one. I think the problem is in comparsion. Also, I tried this:
bool operator == ( const KeyStruct& o ) const
{
return keydata1 == o.keydata1 &&
keydata2 == o.keydata2 &&
keydata3 == o.keydata3;
}
But it seems QMultiMap
just doesn't use this code in my case.
Any data structure ( to my knowledge) that requires an
operator<()
to function has also the condition that:This seems trivial, but in your case, it is possible that
A<B && B<A
. For instance ifA.keydata1 < B.keydata1
butA.keydata2 > B.keydata2
.To fix this you should write your operator something like this: