Declaring an object before initializing it in c++

Question

Is it possible to declare a variable in c++ without instantiating it? I want to do something like this:

Animal a;
if( happyDay() ) 
    a( \"puppies\" ); //c         


        

Answer 1

The best work around is to use pointer.

Animal a*;
if( happyDay() ) 
    a = new Animal( "puppies" ); //constructor call
else
    a = new Animal( "toads" );

Answer 2

You can also use std::move:

class Ball {
private:
        // This is initialized, but not as needed
        sf::Sprite ball;
public:
        Ball() {
                texture.loadFromFile("ball.png");
                // This is a local object, not the same as the class member.
                sf::Sprite ball2(texture);
                // move it
                this->ball=std::move(ball2);
        }
...

Answer 3

You can't do this directly in C++ since the object is constructed when you define it with the default constructor.

You could, however, run a parameterized constructor to begin with:

Animal a(getAppropriateString());

Or you could actually use something like the ?: operator to determine the correct string. (Update: @Greg gave the syntax for this. See that answer)

Answer 4

You can't declare a variable without calling a constructor. However, in your example you could do the following:

Animal a(happyDay() ? "puppies" : "toads");