Adding empty element to declared container without declaring type of element
When we use a complicated container in C++, like
std::vector<std::map<std::string, std::set<std::string>>> table;
The only way to add an empty map (which may represent a row or column) is to initialize a new element and push it back. For example with
table.push_back(std::map<std::string, std::set<std::string>>());
Is there any way to avoid redeclaring the type, and just adding the correct typed element?
c++ c++11
edited 23 hours ago
Mohammad Usman
21.4k124658
asked yesterday
VineetVineet
354411
add a comment |
When we use a complicated container in C++, like
std::vector<std::map<std::string, std::set<std::string>>> table;
The only way to add an empty map (which may represent a row or column) is to initialize a new element and push it back. For example with
table.push_back(std::map<std::string, std::set<std::string>>());
Is there any way to avoid redeclaring the type, and just adding the correct typed element?
c++ c++11
edited 23 hours ago
Mohammad Usman
21.4k124658
asked yesterday
VineetVineet
354411
add a comment |
When we use a complicated container in C++, like
std::vector<std::map<std::string, std::set<std::string>>> table;
The only way to add an empty map (which may represent a row or column) is to initialize a new element and push it back. For example with
table.push_back(std::map<std::string, std::set<std::string>>());
Is there any way to avoid redeclaring the type, and just adding the correct typed element?
c++ c++11
edited 23 hours ago
Mohammad Usman
21.4k124658
asked yesterday
VineetVineet
354411
When we use a complicated container in C++, like
std::vector<std::map<std::string, std::set<std::string>>> table;
The only way to add an empty map (which may represent a row or column) is to initialize a new element and push it back. For example with
table.push_back(std::map<std::string, std::set<std::string>>());
Is there any way to avoid redeclaring the type, and just adding the correct typed element?
c++ c++11
c++ c++11
edited 23 hours ago
Mohammad Usman
21.4k124658
asked yesterday
VineetVineet
354411
edited 23 hours ago
Mohammad Usman
21.4k124658
asked yesterday
VineetVineet
354411
edited 23 hours ago
Mohammad Usman
21.4k124658
edited 23 hours ago
Mohammad Usman
21.4k124658
edited 23 hours ago
Mohammad Usman
21.4k124658
21.4k124658
asked yesterday
VineetVineet
354411
asked yesterday
VineetVineet
354411
asked yesterday
VineetVineet
354411
354411
add a comment |
add a comment |
4 Answers
4
active
oldest
votes
From CLion's IntelliSense, I later found that one useful method is emplace_back(). This constructs a new object of correct type and adds it to the end of the vector.
table.emplace_back();
answered yesterday
VineetVineet
354411
add a comment |
You can take advantage of copy-list-initialization (since C++11) and just write
table.push_back({});
answered yesterday
songyuanyaosongyuanyao
93.6k11182248
add a comment |
Before C++11 sometimes I use x.resize(x.size()+1), in C++11 or later you can use x.push_back({}).
answered yesterday
65026502
87.6k13115218
add a comment |
Though the other answers are correct, I will add that if you couldn't take that approach, you could have benefitted from declaring some type aliases to shorten that container type name.
I can of course only guess at the logical meaning of your containers, which is another thing that this fixes!
using PhilosopherNameType = std::string;
using NeighboursType = std::set<PhilosopherNameType>;
using NeighbourMapType = std::map<PhilosopherNameType, NeighboursType>;
std::vector<NeighbourMapType> table;
table.push_back(NeighbourMapType());
I mention this because you can likely still benefit from this in other places.
answered 17 hours ago
Lightness Races in OrbitLightness Races in Orbit
294k54477809
1
agreed. Along the same lines are the types that the STL gives you (vector::value_type iirc)
– sudo rm -rf slash
2 hours ago
add a comment |
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4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
From CLion's IntelliSense, I later found that one useful method is emplace_back(). This constructs a new object of correct type and adds it to the end of the vector.
table.emplace_back();
answered yesterday
VineetVineet
354411
add a comment |
From CLion's IntelliSense, I later found that one useful method is emplace_back(). This constructs a new object of correct type and adds it to the end of the vector.
table.emplace_back();
answered yesterday
VineetVineet
354411
add a comment |
From CLion's IntelliSense, I later found that one useful method is emplace_back(). This constructs a new object of correct type and adds it to the end of the vector.
table.emplace_back();
answered yesterday
VineetVineet
354411
From CLion's IntelliSense, I later found that one useful method is emplace_back(). This constructs a new object of correct type and adds it to the end of the vector.
table.emplace_back();
answered yesterday
VineetVineet
354411
edited yesterday
answered yesterday
VineetVineet
354411
answered yesterday
VineetVineet
354411
answered yesterday
VineetVineet
354411
354411
add a comment |
add a comment |
You can take advantage of copy-list-initialization (since C++11) and just write
table.push_back({});
answered yesterday
songyuanyaosongyuanyao
93.6k11182248
add a comment |
You can take advantage of copy-list-initialization (since C++11) and just write
table.push_back({});
answered yesterday
songyuanyaosongyuanyao
93.6k11182248
add a comment |
You can take advantage of copy-list-initialization (since C++11) and just write
table.push_back({});
answered yesterday
songyuanyaosongyuanyao
93.6k11182248
You can take advantage of copy-list-initialization (since C++11) and just write
table.push_back({});
answered yesterday
songyuanyaosongyuanyao
93.6k11182248
edited yesterday
answered yesterday
songyuanyaosongyuanyao
93.6k11182248
answered yesterday
songyuanyaosongyuanyao
93.6k11182248
answered yesterday
songyuanyaosongyuanyao
93.6k11182248
93.6k11182248
add a comment |
add a comment |
Before C++11 sometimes I use x.resize(x.size()+1), in C++11 or later you can use x.push_back({}).
answered yesterday
65026502
87.6k13115218
add a comment |
Before C++11 sometimes I use x.resize(x.size()+1), in C++11 or later you can use x.push_back({}).
answered yesterday
65026502
87.6k13115218
add a comment |
Before C++11 sometimes I use x.resize(x.size()+1), in C++11 or later you can use x.push_back({}).
answered yesterday
65026502
87.6k13115218
Before C++11 sometimes I use x.resize(x.size()+1), in C++11 or later you can use x.push_back({}).
answered yesterday
65026502
87.6k13115218
answered yesterday
65026502
87.6k13115218
answered yesterday
65026502
87.6k13115218
answered yesterday
65026502
87.6k13115218
87.6k13115218
add a comment |
add a comment |
Though the other answers are correct, I will add that if you couldn't take that approach, you could have benefitted from declaring some type aliases to shorten that container type name.
I can of course only guess at the logical meaning of your containers, which is another thing that this fixes!
using PhilosopherNameType = std::string;
using NeighboursType = std::set<PhilosopherNameType>;
using NeighbourMapType = std::map<PhilosopherNameType, NeighboursType>;
std::vector<NeighbourMapType> table;
table.push_back(NeighbourMapType());
I mention this because you can likely still benefit from this in other places.
answered 17 hours ago
Lightness Races in OrbitLightness Races in Orbit
294k54477809
1
agreed. Along the same lines are the types that the STL gives you (vector::value_type iirc)
– sudo rm -rf slash
2 hours ago
add a comment |
Though the other answers are correct, I will add that if you couldn't take that approach, you could have benefitted from declaring some type aliases to shorten that container type name.
I can of course only guess at the logical meaning of your containers, which is another thing that this fixes!
using PhilosopherNameType = std::string;
using NeighboursType = std::set<PhilosopherNameType>;
using NeighbourMapType = std::map<PhilosopherNameType, NeighboursType>;
std::vector<NeighbourMapType> table;
table.push_back(NeighbourMapType());
I mention this because you can likely still benefit from this in other places.
answered 17 hours ago
Lightness Races in OrbitLightness Races in Orbit
294k54477809
1
agreed. Along the same lines are the types that the STL gives you (vector::value_type iirc)
– sudo rm -rf slash
2 hours ago
add a comment |
Though the other answers are correct, I will add that if you couldn't take that approach, you could have benefitted from declaring some type aliases to shorten that container type name.
I can of course only guess at the logical meaning of your containers, which is another thing that this fixes!
using PhilosopherNameType = std::string;
using NeighboursType = std::set<PhilosopherNameType>;
using NeighbourMapType = std::map<PhilosopherNameType, NeighboursType>;
std::vector<NeighbourMapType> table;
table.push_back(NeighbourMapType());
I mention this because you can likely still benefit from this in other places.
answered 17 hours ago
Lightness Races in OrbitLightness Races in Orbit
294k54477809
Though the other answers are correct, I will add that if you couldn't take that approach, you could have benefitted from declaring some type aliases to shorten that container type name.
I can of course only guess at the logical meaning of your containers, which is another thing that this fixes!
using PhilosopherNameType = std::string;
using NeighboursType = std::set<PhilosopherNameType>;
using NeighbourMapType = std::map<PhilosopherNameType, NeighboursType>;
std::vector<NeighbourMapType> table;
table.push_back(NeighbourMapType());
I mention this because you can likely still benefit from this in other places.
answered 17 hours ago
Lightness Races in OrbitLightness Races in Orbit
294k54477809
answered 17 hours ago
Lightness Races in OrbitLightness Races in Orbit
294k54477809
answered 17 hours ago
Lightness Races in OrbitLightness Races in Orbit
294k54477809
answered 17 hours ago
Lightness Races in OrbitLightness Races in Orbit
294k54477809
294k54477809
1
agreed. Along the same lines are the types that the STL gives you (vector::value_type iirc)
– sudo rm -rf slash
2 hours ago
add a comment |
1
agreed. Along the same lines are the types that the STL gives you (vector::value_type iirc)
– sudo rm -rf slash
2 hours ago
1
1
agreed. Along the same lines are the types that the STL gives you (vector::value_type iirc)
– sudo rm -rf slash
2 hours ago
agreed. Along the same lines are the types that the STL gives you (vector::value_type iirc)
– sudo rm -rf slash
2 hours ago
add a comment |
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