Question about "auto" keyword in combination with "new"
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Hi all C++ gurus, I have a question about
autousage with pointers.
Is there a difference for this two declaration?auto var1 = new MyClass(); auto* var2 = new MyClass();Is one preferable to ensure C++ compiler compatibility (msvc, gcc, clang)?
Or those it not mather?It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. (Sherlock Holmes)
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Hi all C++ gurus, I have a question about
autousage with pointers.
Is there a difference for this two declaration?auto var1 = new MyClass(); auto* var2 = new MyClass();Is one preferable to ensure C++ compiler compatibility (msvc, gcc, clang)?
Or those it not mather?Hi @KroMignon,
Is there a difference for this two declaration?
auto var1 = new MyClass();
auto* var2 = new MyClass();No, they are equal.
Is one preferable to ensure C++ compiler compatibility (msvc, gcc, clang)?
I'm not sure if there are compiler differences, they should all handle both without problems; so it's more a matter of style.
E.g. in QtCreator we use
auto ptr = new Ptr();(without asterisk).Regards
Qt has to stay free or it will die.
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Hi @KroMignon,
Is there a difference for this two declaration?
auto var1 = new MyClass();
auto* var2 = new MyClass();No, they are equal.
Is one preferable to ensure C++ compiler compatibility (msvc, gcc, clang)?
I'm not sure if there are compiler differences, they should all handle both without problems; so it's more a matter of style.
E.g. in QtCreator we use
auto ptr = new Ptr();(without asterisk).Regards
@aha_1980 said in Question about "auto" keyword in combination with "new":
No, they are equal.
In almost all cases!
A quick google search resulted in this stack overflow thread:
https://stackoverflow.com/questions/12773257/does-auto-type-assignments-of-a-pointer-in-c11-require🤷♂️
Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct
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Q: What does it do?
A: It turns blue. -
@aha_1980 said in Question about "auto" keyword in combination with "new":
No, they are equal.
In almost all cases!
A quick google search resulted in this stack overflow thread:
https://stackoverflow.com/questions/12773257/does-auto-type-assignments-of-a-pointer-in-c11-require🤷♂️
@J-Hilk Thank you for the link, I tried myself a google search before posting my question, but did not find this entry!
@aha_1980 thank you also to take time to reply, I've added a start on all my
autoin combination withnew. It is more "clean" for me, even if it made no real difference. -
@KroMignon said in Question about "auto" keyword in combination with "new":
Is there a difference for this two declaration?
Not sure if you noticed, but if you hover over the "auto" keyword with the mouse in Qt Creator it tells you the type it has deduced most of the time.
C++ is a perfectly valid school of magic.
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@KroMignon said in Question about "auto" keyword in combination with "new":
Is there a difference for this two declaration?
Not sure if you noticed, but if you hover over the "auto" keyword with the mouse in Qt Creator it tells you the type it has deduced most of the time.
@KroMignon
Apparently it does have a use:
https://en.cppreference.com/w/cpp/language/autoIs particular:
auto i = 0, *p = &i;In this case auto is deduced as int. So *p is a pointer to int.
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@fcarney said in Question about "auto" keyword in combination with "new":
auto i = 0, *p = &i;
But this is nothing special to the auto keyword. It's C basic.
