I have a struct with two members, for example:
struct DataSet {
int x;
int y;
};
..., and i have to access those in a method, but only one at a time, for example:
void foo(StructMember dsm) { // ("StructMember" does not exist)
DataSet ds;
ds.x = 4;
ds.y = 6;
std::cout << ds.dsm * ds.dsm << std::endl;
}
foo(x);
foo(y);
Output i wish to have:
16
36
What should I do when I have to solve a problem like this? Is there a data type which can access a member?
Yes, you can use a pointer-to-member. The syntax for the type is TypeOfMember TypeOfStruct::*
, and to access you do struct_variable.*pointer_variable
using StructMember = int DataSet::*; // Pointer to a member of `DataSet` of type `int`
void foo(StructMember dsm) {
DataSet ds;
ds.x = 4;
ds.y = 6;
std::cout << ds.*dsm * ds.*dsm << std::endl;
}
int main() {
foo(&DataSet::x);
foo(&DataSet::y);
}
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