CODEWITHSUNDEEP
c++constructor
mrgloom
mrgloom

Reputation: 21632

is there any difference between these two pieces of code? (temp variable)

Is there any difference between these two pieces of code?

CPoint temp(x,y);

some_func(temp);

and

some_func(CPoint(x,y));

Upvotes: 0

Views: 67

Answers (2)

arthur.sw
arthur.sw

Reputation: 11639

Yes, in the first case, the temp var will not be destroyed until the end of the scope. In the second case it will be.

If your function some_func() takes a non const reference as a parameter, the second will not compile since you can not have a reference to something which will be destroyed right away (when some_func returns).

In the first case, if your some_func() function takes a reference, you should be aware that the temp variable will only exist until the current scope ends.

Upvotes: 2

harmic
harmic

Reputation: 30587

The lifetime of the CPoint objects is different.

In the first case, a variable named 'temp' is created. It will not be destroyed until after the scope within which it is declared is exited.

In the second case, a true temporary value is created and passed to the function, which will be destroyed as soon as some_func has returned.

Upvotes: 2

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