C++ : good practice of declare map of custom type
2
I am trying to define a map like below within my MyTreeNode class:
std::unordered_map<int, MyTreeNode> children_map;
This seems to be fine. However, I am wondering would it be better to define the map using the pointer like?
std::unordered_map<int, MyTreeNode*> children_map;
For my specific case, I have
class MyTreeNode {
// some code
std::unordered_map<int, MyTreeNode> children_map; // line_1
// std::unordered_map<int, MyTreeNode*> children_map; // line_2
}
Is there a good practice for such scenario? Should I use line_1 or line_2? Thanks!
c++ pointers treenode
asked Dec 31 '18 at 23:17
EdamameEdamame
4,7252379157
|
show 5 more comments
2
I am trying to define a map like below within my MyTreeNode class:
std::unordered_map<int, MyTreeNode> children_map;
This seems to be fine. However, I am wondering would it be better to define the map using the pointer like?
std::unordered_map<int, MyTreeNode*> children_map;
For my specific case, I have
class MyTreeNode {
// some code
std::unordered_map<int, MyTreeNode> children_map; // line_1
// std::unordered_map<int, MyTreeNode*> children_map; // line_2
}
Is there a good practice for such scenario? Should I use line_1 or line_2? Thanks!
c++ pointers treenode
asked Dec 31 '18 at 23:17
EdamameEdamame
4,7252379157
7
That depends entirely on the context. If you already have the instances ofMyTreeNodestored e.g. in a vector and only want to use thestd::unordered_mapas a kind of index into the vector then use the second version. If the map owns theMyTreeNodeinstances then use the first version.
– Corristo
Dec 31 '18 at 23:19
1
@edamame - Um..... Is this supposed to be a map that holds custom types, or is it some device that holds entities in special clothing?
– enhzflep
Dec 31 '18 at 23:26
@enhzflep it is a map that holds custom types. Thanks!
– Edamame
Dec 31 '18 at 23:31
2
If you are able to do either then use the first one (don't use pointers if you don't have to). Otherwise they have different uses.
– Galik
Dec 31 '18 at 23:45
1
If you are relying onunordered_mapfor your search tree, why not just use a singleunordered_mapfor all of your nodes? What advantage does a tree structure give you for children that a singleunordered_mapwould not be able to provide?
– jxh
Dec 31 '18 at 23:57
|
show 5 more comments
2
2
2
I am trying to define a map like below within my MyTreeNode class:
std::unordered_map<int, MyTreeNode> children_map;
This seems to be fine. However, I am wondering would it be better to define the map using the pointer like?
std::unordered_map<int, MyTreeNode*> children_map;
For my specific case, I have
class MyTreeNode {
// some code
std::unordered_map<int, MyTreeNode> children_map; // line_1
// std::unordered_map<int, MyTreeNode*> children_map; // line_2
}
Is there a good practice for such scenario? Should I use line_1 or line_2? Thanks!
c++ pointers treenode
asked Dec 31 '18 at 23:17
EdamameEdamame
4,7252379157
I am trying to define a map like below within my MyTreeNode class:
std::unordered_map<int, MyTreeNode> children_map;
This seems to be fine. However, I am wondering would it be better to define the map using the pointer like?
std::unordered_map<int, MyTreeNode*> children_map;
For my specific case, I have
class MyTreeNode {
// some code
std::unordered_map<int, MyTreeNode> children_map; // line_1
// std::unordered_map<int, MyTreeNode*> children_map; // line_2
}
Is there a good practice for such scenario? Should I use line_1 or line_2? Thanks!
c++ pointers treenode
c++ pointers treenode
asked Dec 31 '18 at 23:17
EdamameEdamame
4,7252379157
asked Dec 31 '18 at 23:17
EdamameEdamame
4,7252379157
edited Dec 31 '18 at 23:40
Edamame
asked Dec 31 '18 at 23:17
EdamameEdamame
4,7252379157
asked Dec 31 '18 at 23:17
EdamameEdamame
4,7252379157
asked Dec 31 '18 at 23:17
EdamameEdamame
4,7252379157
4,7252379157
7
That depends entirely on the context. If you already have the instances ofMyTreeNodestored e.g. in a vector and only want to use thestd::unordered_mapas a kind of index into the vector then use the second version. If the map owns theMyTreeNodeinstances then use the first version.
– Corristo
Dec 31 '18 at 23:19
1
@edamame - Um..... Is this supposed to be a map that holds custom types, or is it some device that holds entities in special clothing?
– enhzflep
Dec 31 '18 at 23:26
@enhzflep it is a map that holds custom types. Thanks!
– Edamame
Dec 31 '18 at 23:31
2
If you are able to do either then use the first one (don't use pointers if you don't have to). Otherwise they have different uses.
– Galik
Dec 31 '18 at 23:45
1
If you are relying onunordered_mapfor your search tree, why not just use a singleunordered_mapfor all of your nodes? What advantage does a tree structure give you for children that a singleunordered_mapwould not be able to provide?
– jxh
Dec 31 '18 at 23:57
|
show 5 more comments
7
That depends entirely on the context. If you already have the instances ofMyTreeNodestored e.g. in a vector and only want to use thestd::unordered_mapas a kind of index into the vector then use the second version. If the map owns theMyTreeNodeinstances then use the first version.
– Corristo
Dec 31 '18 at 23:19
1
@edamame - Um..... Is this supposed to be a map that holds custom types, or is it some device that holds entities in special clothing?
– enhzflep
Dec 31 '18 at 23:26
@enhzflep it is a map that holds custom types. Thanks!
– Edamame
Dec 31 '18 at 23:31
2
If you are able to do either then use the first one (don't use pointers if you don't have to). Otherwise they have different uses.
– Galik
Dec 31 '18 at 23:45
1
If you are relying onunordered_mapfor your search tree, why not just use a singleunordered_mapfor all of your nodes? What advantage does a tree structure give you for children that a singleunordered_mapwould not be able to provide?
– jxh
Dec 31 '18 at 23:57
7
7
That depends entirely on the context. If you already have the instances of
MyTreeNode stored e.g. in a vector and only want to use the std::unordered_map as a kind of index into the vector then use the second version. If the map owns the MyTreeNode instances then use the first version.– Corristo
Dec 31 '18 at 23:19
That depends entirely on the context. If you already have the instances of
MyTreeNode stored e.g. in a vector and only want to use the std::unordered_map as a kind of index into the vector then use the second version. If the map owns the MyTreeNode instances then use the first version.– Corristo
Dec 31 '18 at 23:19
1
1
@edamame - Um..... Is this supposed to be a map that holds custom types, or is it some device that holds entities in special clothing?
– enhzflep
Dec 31 '18 at 23:26
@edamame - Um..... Is this supposed to be a map that holds custom types, or is it some device that holds entities in special clothing?
– enhzflep
Dec 31 '18 at 23:26
@enhzflep it is a map that holds custom types. Thanks!
– Edamame
Dec 31 '18 at 23:31
@enhzflep it is a map that holds custom types. Thanks!
– Edamame
Dec 31 '18 at 23:31
2
2
If you are able to do either then use the first one (don't use pointers if you don't have to). Otherwise they have different uses.
– Galik
Dec 31 '18 at 23:45
If you are able to do either then use the first one (don't use pointers if you don't have to). Otherwise they have different uses.
– Galik
Dec 31 '18 at 23:45
1
1
If you are relying on
unordered_map for your search tree, why not just use a single unordered_map for all of your nodes? What advantage does a tree structure give you for children that a single unordered_map would not be able to provide?– jxh
Dec 31 '18 at 23:57
If you are relying on
unordered_map for your search tree, why not just use a single unordered_map for all of your nodes? What advantage does a tree structure give you for children that a single unordered_map would not be able to provide?– jxh
Dec 31 '18 at 23:57
|
show 5 more comments
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7
That depends entirely on the context. If you already have the instances of
MyTreeNodestored e.g. in a vector and only want to use thestd::unordered_mapas a kind of index into the vector then use the second version. If the map owns theMyTreeNodeinstances then use the first version.– Corristo
Dec 31 '18 at 23:19
1
@edamame - Um..... Is this supposed to be a map that holds custom types, or is it some device that holds entities in special clothing?
– enhzflep
Dec 31 '18 at 23:26
@enhzflep it is a map that holds custom types. Thanks!
– Edamame
Dec 31 '18 at 23:31
2
If you are able to do either then use the first one (don't use pointers if you don't have to). Otherwise they have different uses.
– Galik
Dec 31 '18 at 23:45
1
If you are relying on
unordered_mapfor your search tree, why not just use a singleunordered_mapfor all of your nodes? What advantage does a tree structure give you for children that a singleunordered_mapwould not be able to provide?– jxh
Dec 31 '18 at 23:57