C++ how to initialize and fill 2D vector of class
up vote
-2
down vote
favorite
I'm fairly new to c++, trying to figure out how to use vector's syntax.
Say I want to initialize and fill a 2D vector based on input
Cell
int x, y;
public:
Cell();
....
;
Grid
vector<vector<Cell>> theGrid;
public:
void init(int n);
;
whats wrong with this
void Grid::init(int n)
for (int i = 0; i < n; ++i)
for (int j = 0; j < n; ++j)
Cell c;
theGrid.[i].emplace_back(c);
c++
asked Nov 11 at 3:39
Steven j C
11
add a comment |
up vote
-2
down vote
favorite
I'm fairly new to c++, trying to figure out how to use vector's syntax.
Say I want to initialize and fill a 2D vector based on input
Cell
int x, y;
public:
Cell();
....
;
Grid
vector<vector<Cell>> theGrid;
public:
void init(int n);
;
whats wrong with this
void Grid::init(int n)
for (int i = 0; i < n; ++i)
for (int j = 0; j < n; ++j)
Cell c;
theGrid.[i].emplace_back(c);
c++
asked Nov 11 at 3:39
Steven j C
11
theGrid.[i].emplace_back(c);should betheGrid[i].emplace_back(c);
– macroland
Nov 11 at 3:42
1
theGrid.resize(n, vector<Cell>(n));is all that's needed.
– Igor Tandetnik
Nov 11 at 3:45
@IgorTandetnikresizeis not suitable in case if the vector is not empty.
– S.M.
Nov 11 at 4:02
classdefinition inC++requiresclassorstructkeyword.
– JiaHao Xu
Nov 11 at 4:10
add a comment |
up vote
-2
down vote
favorite
up vote
-2
down vote
favorite
I'm fairly new to c++, trying to figure out how to use vector's syntax.
Say I want to initialize and fill a 2D vector based on input
Cell
int x, y;
public:
Cell();
....
;
Grid
vector<vector<Cell>> theGrid;
public:
void init(int n);
;
whats wrong with this
void Grid::init(int n)
for (int i = 0; i < n; ++i)
for (int j = 0; j < n; ++j)
Cell c;
theGrid.[i].emplace_back(c);
c++
asked Nov 11 at 3:39
Steven j C
11
I'm fairly new to c++, trying to figure out how to use vector's syntax.
Say I want to initialize and fill a 2D vector based on input
Cell
int x, y;
public:
Cell();
....
;
Grid
vector<vector<Cell>> theGrid;
public:
void init(int n);
;
whats wrong with this
void Grid::init(int n)
for (int i = 0; i < n; ++i)
for (int j = 0; j < n; ++j)
Cell c;
theGrid.[i].emplace_back(c);
c++
c++
asked Nov 11 at 3:39
Steven j C
11
asked Nov 11 at 3:39
Steven j C
11
asked Nov 11 at 3:39
Steven j C
11
asked Nov 11 at 3:39
Steven j C
11
asked Nov 11 at 3:39
Steven j C
11
11
theGrid.[i].emplace_back(c);should betheGrid[i].emplace_back(c);
– macroland
Nov 11 at 3:42
1
theGrid.resize(n, vector<Cell>(n));is all that's needed.
– Igor Tandetnik
Nov 11 at 3:45
@IgorTandetnikresizeis not suitable in case if the vector is not empty.
– S.M.
Nov 11 at 4:02
classdefinition inC++requiresclassorstructkeyword.
– JiaHao Xu
Nov 11 at 4:10
add a comment |
theGrid.[i].emplace_back(c);should betheGrid[i].emplace_back(c);
– macroland
Nov 11 at 3:42
1
theGrid.resize(n, vector<Cell>(n));is all that's needed.
– Igor Tandetnik
Nov 11 at 3:45
@IgorTandetnikresizeis not suitable in case if the vector is not empty.
– S.M.
Nov 11 at 4:02
classdefinition inC++requiresclassorstructkeyword.
– JiaHao Xu
Nov 11 at 4:10
theGrid.[i].emplace_back(c); should be theGrid[i].emplace_back(c);– macroland
Nov 11 at 3:42
theGrid.[i].emplace_back(c); should be theGrid[i].emplace_back(c);– macroland
Nov 11 at 3:42
1
1
theGrid.resize(n, vector<Cell>(n)); is all that's needed.– Igor Tandetnik
Nov 11 at 3:45
theGrid.resize(n, vector<Cell>(n)); is all that's needed.– Igor Tandetnik
Nov 11 at 3:45
@IgorTandetnik
resize is not suitable in case if the vector is not empty.– S.M.
Nov 11 at 4:02
@IgorTandetnik
resize is not suitable in case if the vector is not empty.– S.M.
Nov 11 at 4:02
class definition in C++ requires class or struct keyword.– JiaHao Xu
Nov 11 at 4:10
class definition in C++ requires class or struct keyword.– JiaHao Xu
Nov 11 at 4:10
add a comment |
2 Answers
2
active
oldest
votes
up vote
0
down vote
accepted
You have several problems there: syntax errors, access out of bounds, using loops instead of the STL power.
void Grid::init(int n)
theGrid = std::vector<vector<Cell>>(n, std::vector<Cell>(n, Cell()));
answered Nov 11 at 3:45
S.M.
5,64931525
so what is a more "vector" way to access every Cell in this 2D structure
– Steven j C
Nov 11 at 3:53
foreach variant of theforloop.
– S.M.
Nov 11 at 3:55
add a comment |
up vote
0
down vote
As for your code:
theGrid.[i].emplace_back(c);
Here you have a ".[i].", so that is syntax error... So, we have to write the syntax correctly which yields:
theGrid[i].emplace_back(c);
Or:
theGrid.at(i).emplace_back(c);
You don't even need to do that... Just use the vector's constructor:
theGrid = std::vector<std::vector<Cell>>(n, std::vector<Cell>(n));
answered Nov 11 at 3:46
Ruks
778211
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
0
down vote
accepted
You have several problems there: syntax errors, access out of bounds, using loops instead of the STL power.
void Grid::init(int n)
theGrid = std::vector<vector<Cell>>(n, std::vector<Cell>(n, Cell()));
answered Nov 11 at 3:45
S.M.
5,64931525
so what is a more "vector" way to access every Cell in this 2D structure
– Steven j C
Nov 11 at 3:53
foreach variant of theforloop.
– S.M.
Nov 11 at 3:55
add a comment |
up vote
0
down vote
accepted
You have several problems there: syntax errors, access out of bounds, using loops instead of the STL power.
void Grid::init(int n)
theGrid = std::vector<vector<Cell>>(n, std::vector<Cell>(n, Cell()));
answered Nov 11 at 3:45
S.M.
5,64931525
so what is a more "vector" way to access every Cell in this 2D structure
– Steven j C
Nov 11 at 3:53
foreach variant of theforloop.
– S.M.
Nov 11 at 3:55
add a comment |
up vote
0
down vote
accepted
up vote
0
down vote
accepted
You have several problems there: syntax errors, access out of bounds, using loops instead of the STL power.
void Grid::init(int n)
theGrid = std::vector<vector<Cell>>(n, std::vector<Cell>(n, Cell()));
answered Nov 11 at 3:45
S.M.
5,64931525
You have several problems there: syntax errors, access out of bounds, using loops instead of the STL power.
void Grid::init(int n)
theGrid = std::vector<vector<Cell>>(n, std::vector<Cell>(n, Cell()));
answered Nov 11 at 3:45
S.M.
5,64931525
edited Nov 11 at 3:56
answered Nov 11 at 3:45
S.M.
5,64931525
answered Nov 11 at 3:45
S.M.
5,64931525
answered Nov 11 at 3:45
S.M.
5,64931525
5,64931525
so what is a more "vector" way to access every Cell in this 2D structure
– Steven j C
Nov 11 at 3:53
foreach variant of theforloop.
– S.M.
Nov 11 at 3:55
add a comment |
so what is a more "vector" way to access every Cell in this 2D structure
– Steven j C
Nov 11 at 3:53
foreach variant of theforloop.
– S.M.
Nov 11 at 3:55
so what is a more "vector" way to access every Cell in this 2D structure
– Steven j C
Nov 11 at 3:53
so what is a more "vector" way to access every Cell in this 2D structure
– Steven j C
Nov 11 at 3:53
foreach variant of the
for loop.– S.M.
Nov 11 at 3:55
foreach variant of the
for loop.– S.M.
Nov 11 at 3:55
add a comment |
up vote
0
down vote
As for your code:
theGrid.[i].emplace_back(c);
Here you have a ".[i].", so that is syntax error... So, we have to write the syntax correctly which yields:
theGrid[i].emplace_back(c);
Or:
theGrid.at(i).emplace_back(c);
You don't even need to do that... Just use the vector's constructor:
theGrid = std::vector<std::vector<Cell>>(n, std::vector<Cell>(n));
answered Nov 11 at 3:46
Ruks
778211
add a comment |
up vote
0
down vote
As for your code:
theGrid.[i].emplace_back(c);
Here you have a ".[i].", so that is syntax error... So, we have to write the syntax correctly which yields:
theGrid[i].emplace_back(c);
Or:
theGrid.at(i).emplace_back(c);
You don't even need to do that... Just use the vector's constructor:
theGrid = std::vector<std::vector<Cell>>(n, std::vector<Cell>(n));
answered Nov 11 at 3:46
Ruks
778211
add a comment |
up vote
0
down vote
up vote
0
down vote
As for your code:
theGrid.[i].emplace_back(c);
Here you have a ".[i].", so that is syntax error... So, we have to write the syntax correctly which yields:
theGrid[i].emplace_back(c);
Or:
theGrid.at(i).emplace_back(c);
You don't even need to do that... Just use the vector's constructor:
theGrid = std::vector<std::vector<Cell>>(n, std::vector<Cell>(n));
answered Nov 11 at 3:46
Ruks
778211
As for your code:
theGrid.[i].emplace_back(c);
Here you have a ".[i].", so that is syntax error... So, we have to write the syntax correctly which yields:
theGrid[i].emplace_back(c);
Or:
theGrid.at(i).emplace_back(c);
You don't even need to do that... Just use the vector's constructor:
theGrid = std::vector<std::vector<Cell>>(n, std::vector<Cell>(n));
answered Nov 11 at 3:46
Ruks
778211
answered Nov 11 at 3:46
Ruks
778211
answered Nov 11 at 3:46
Ruks
778211
answered Nov 11 at 3:46
Ruks
778211
778211
add a comment |
add a comment |
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theGrid.[i].emplace_back(c);should betheGrid[i].emplace_back(c);– macroland
Nov 11 at 3:42
1
theGrid.resize(n, vector<Cell>(n));is all that's needed.– Igor Tandetnik
Nov 11 at 3:45
@IgorTandetnik
resizeis not suitable in case if the vector is not empty.– S.M.
Nov 11 at 4:02
classdefinition inC++requiresclassorstructkeyword.– JiaHao Xu
Nov 11 at 4:10