CODEWITHSUNDEEP
c++c++11
quant
quant

Reputation: 23052

How do I create and initialise a simple struct without providing a constructor?

Suppose I have this type:

struct T
{
  SomeType a;
  OtherType b;
};

I think there is some way to declare an object of type T and defining the initialised values of a and b in line, but I can't remember how this worked, or even what it's called so I can look it up. Something like T t(a, b) where a and b are of type SomeType and OtherType respectively.

How do I achieve this without declaring a constructor, and what is it called?

Upvotes: 1

Views: 255

Answers (3)

nwp
nwp

Reputation: 9991

You can write T t = {a, b}. That only works with PODs aggregates though (or with a propper constructors of course).

Upvotes: 4

Gavin
Gavin

Reputation: 135

C++11 suports unified inicializatoin list with "{}", which means you can init. classes with "{}" as a struct before you can initialize the the struct like this

T t{someTypeA, otherTypeB};// someTypeA and someTypeB must be defined

here is a simple test code

#include <iostream>
using namespace std;

class B
{
public:
    int a;
};

class C
{
public:
    int a;
};

struct A
{
    B b;
    C c;
};

int main(int argc, char** argv) 
{ 
    B b;
    C c;
    b.a = 1;
    c.a = 2;
    A a{b, c};
    cout << a.b.a << a.c.a << endl;
    return 0; 
}

Upvotes: 0

Klaus
Klaus

Reputation: 25603

You tagged with c++11, so do very simply this:

#include <iostream>

struct T
{   
    int a;
    float b;
};  


int main()
{   
    T t{1,2.2};

    std::cout << t.a << ":" << t.b << std::endl;

}

Upvotes: 3

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