How to make an array of structs? [closed] - c++

Question

Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 8 years ago.
Improve this question
I would like to know if I can make an array of structs, then use it in a foreach loop.
struct A { int a; };
struct B { int b; };
struct C { float c; };
And then:
int main()
{
A a; B b; C c;
//Here I want to make an array of a, b and c,
//then use it in for loop with the ints and floats.
}`

Answer 1

You can't safely make an array of unrelated types in C++.
If you have the need to put objects together in a container, then they are probably somewhat related : you should think about adding a common base class to A, B and C, and then manipulate an array (or vector...) of (smart) base class pointers.
However, think about the possible alternative of defining a type encapsulating your struct, instead of declaring this "array" :
struct T {
A obj1;
B obj2;
C obj3;
};
Note :
If you really need type erasure, then boost::any or boost::variant are very handy to encapsulate objects or any type.

Answer 2

Of course you can, but you cannot make an array of unrelated types/structs without using external libraries:
#include <iostream>
struct Person
{
std::string name;
int age;
std::string job;
};
int main()
{
Person people[10];
//I am a normal one.
for(int i=0; i<10; ++i)
{
people[i].name = "usar";
people[i].age = i;
people[i].job = "Astronaut";
}
//foreach loop
for(Person p: people)
{
std::cout << "Name: "<< p.name << "\n";
std::cout << "Age: "<< p.age << "\n";
std::cout << "Job: "<< p.job << "\n";
}
return 0;
}

Answer 3

Yes Just create it just as other types. Assume that we have a struct of Car
struct Car
{
int engine;
string brandName;
};
You can create it like
Car list[2]={{3000, "BMW"},{2200, "Mercedes-Benz"}};
or just
Car list[2];

Answer 4

If you want to have "array" of different types, it is technically possible in C++ though not simple. At least not for novice C++ programmers. First of all you would need to use non trivial data type like boost::variant or std::tuple, second - accessing that data will require template metaprogramming, which is also not easy for beginners. But most probably your problem has simpler solution and can be solved more easily, you are just looking into wrong direction.

Answer 5

struct Base
{
virtual ~Base(){}
virtual int GetInt()
{
throw "Not implemented";
return 0;
}
virtual float GetFloat()
{
throw "Not implemented";
return 0.0f;
};
};
struct A : public Base
{
int a;
virtual int GetInt()
{
return a;
}
};
struct B : public Base
{
int b;
virtual int GetInt()
{
return b;
}
};
struct C : public Base
{
float c;
virtual float GetFloat()
{
return c;
}
};
int main()
{
A a; B b; C c;
Base* array[ 3 ] = { &a, &b, &c };
}