A struct inside a struct inside a templated class2019 Community Moderator ElectionWhat's the difference between struct and class in .NET?When should you use a class vs a struct in C++?Use 'class' or 'typename' for template parameters?Why can templates only be implemented in the header file?When to use struct?Where and why do I have to put the “template” and “typename” keywords?Difference between 'struct' and 'typedef struct' in C++?typedef struct vs struct definitionsContainers crash inside structs?Enable method based on boolean template parameter
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A struct inside a struct inside a templated class
2019 Community Moderator ElectionWhat's the difference between struct and class in .NET?When should you use a class vs a struct in C++?Use 'class' or 'typename' for template parameters?Why can templates only be implemented in the header file?When to use struct?Where and why do I have to put the “template” and “typename” keywords?Difference between 'struct' and 'typedef struct' in C++?typedef struct vs struct definitionsContainers crash inside structs?Enable method based on boolean template parameter
I have two structs inside a templated class: struct A and struct B.
struct A contains a vector of B values, and struct B contains a pointer to an A value.
I have a recursive function (called help) that receives a pointer to A as input. I want the function to loop through its vector of B values and recursively call the help function, with each A value stored in the B values, as input.
THE PROBLEM: this gives me a compiler error:
Cannot initialize a parameter of type 'Object<int>::A *' with an lvalue of type 'A *'
Relevant code in my header file:
struct A;
template<typename ValueType>
class Object
public:
struct B
// other things
A* ptr;
;
struct A
// other things
std::vector<B> arr;
;
void callHelp();
void help(A* a);
;
template<typename ValueType>
void Object<ValueType>::callHelp()
help(new A);
template<typename ValueType>
void Object<ValueType>::help(A* a)
if (a == nullptr) return;
for (typename std::vector<B>::iterator it = a->arr.begin(); it != a->arr.end(); it++)
help((*it).ptr);
In main:
int main()
Object<int> o;
o.callHelp();
c++ templates struct
asked Mar 6 at 23:25
Cindy ZhangCindy Zhang
11
add a comment |
I have two structs inside a templated class: struct A and struct B.
struct A contains a vector of B values, and struct B contains a pointer to an A value.
I have a recursive function (called help) that receives a pointer to A as input. I want the function to loop through its vector of B values and recursively call the help function, with each A value stored in the B values, as input.
THE PROBLEM: this gives me a compiler error:
Cannot initialize a parameter of type 'Object<int>::A *' with an lvalue of type 'A *'
Relevant code in my header file:
struct A;
template<typename ValueType>
class Object
public:
struct B
// other things
A* ptr;
;
struct A
// other things
std::vector<B> arr;
;
void callHelp();
void help(A* a);
;
template<typename ValueType>
void Object<ValueType>::callHelp()
help(new A);
template<typename ValueType>
void Object<ValueType>::help(A* a)
if (a == nullptr) return;
for (typename std::vector<B>::iterator it = a->arr.begin(); it != a->arr.end(); it++)
help((*it).ptr);
In main:
int main()
Object<int> o;
o.callHelp();
c++ templates struct
asked Mar 6 at 23:25
Cindy ZhangCindy Zhang
11
Move the forward declarationstruct A;inside of theObjectclass declaration before usingA*.
– πάντα ῥεῖ
Mar 6 at 23:29
add a comment |
I have two structs inside a templated class: struct A and struct B.
struct A contains a vector of B values, and struct B contains a pointer to an A value.
I have a recursive function (called help) that receives a pointer to A as input. I want the function to loop through its vector of B values and recursively call the help function, with each A value stored in the B values, as input.
THE PROBLEM: this gives me a compiler error:
Cannot initialize a parameter of type 'Object<int>::A *' with an lvalue of type 'A *'
Relevant code in my header file:
struct A;
template<typename ValueType>
class Object
public:
struct B
// other things
A* ptr;
;
struct A
// other things
std::vector<B> arr;
;
void callHelp();
void help(A* a);
;
template<typename ValueType>
void Object<ValueType>::callHelp()
help(new A);
template<typename ValueType>
void Object<ValueType>::help(A* a)
if (a == nullptr) return;
for (typename std::vector<B>::iterator it = a->arr.begin(); it != a->arr.end(); it++)
help((*it).ptr);
In main:
int main()
Object<int> o;
o.callHelp();
c++ templates struct
asked Mar 6 at 23:25
Cindy ZhangCindy Zhang
11
I have two structs inside a templated class: struct A and struct B.
struct A contains a vector of B values, and struct B contains a pointer to an A value.
I have a recursive function (called help) that receives a pointer to A as input. I want the function to loop through its vector of B values and recursively call the help function, with each A value stored in the B values, as input.
THE PROBLEM: this gives me a compiler error:
Cannot initialize a parameter of type 'Object<int>::A *' with an lvalue of type 'A *'
Relevant code in my header file:
struct A;
template<typename ValueType>
class Object
public:
struct B
// other things
A* ptr;
;
struct A
// other things
std::vector<B> arr;
;
void callHelp();
void help(A* a);
;
template<typename ValueType>
void Object<ValueType>::callHelp()
help(new A);
template<typename ValueType>
void Object<ValueType>::help(A* a)
if (a == nullptr) return;
for (typename std::vector<B>::iterator it = a->arr.begin(); it != a->arr.end(); it++)
help((*it).ptr);
In main:
int main()
Object<int> o;
o.callHelp();
c++ templates struct
c++ templates struct
asked Mar 6 at 23:25
Cindy ZhangCindy Zhang
11
asked Mar 6 at 23:25
Cindy ZhangCindy Zhang
11
edited Mar 6 at 23:47
Cindy Zhang
asked Mar 6 at 23:25
Cindy ZhangCindy Zhang
11
asked Mar 6 at 23:25
Cindy ZhangCindy Zhang
11
asked Mar 6 at 23:25
Cindy ZhangCindy Zhang
11
11
Move the forward declarationstruct A;inside of theObjectclass declaration before usingA*.
– πάντα ῥεῖ
Mar 6 at 23:29
add a comment |
Move the forward declarationstruct A;inside of theObjectclass declaration before usingA*.
– πάντα ῥεῖ
Mar 6 at 23:29
Move the forward declaration
struct A; inside of the Object class declaration before using A*.– πάντα ῥεῖ
Mar 6 at 23:29
Move the forward declaration
struct A; inside of the Object class declaration before using A*.– πάντα ῥεῖ
Mar 6 at 23:29
add a comment |
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Move the forward declaration
struct A;inside of theObjectclass declaration before usingA*.– πάντα ῥεῖ
Mar 6 at 23:29