What is the difference between
Class class("Test");
and
Class *class = new Class("Test");
Which one is better? Is there even a difference?
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drescherjm
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Lóránt Viktor Gerber
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That's for C, but it should be almost the same: http://stackoverflow.com/questions/5258724/stack-variables-vs-heap-variables – Rakete1111 Mar 18 '17 at 14:51
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1It's stack vs heap allocation. "Which one is better?" It depends...Read up on them. – Arash Mar 18 '17 at 14:57
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1Related: http://stackoverflow.com/questions/408670/stack-static-and-heap-in-c – user4581301 Mar 18 '17 at 15:02
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1@Arash: It's automatic vs dynamic allocation. Read up on them. – Lightness Races in Orbit Mar 18 '17 at 15:07
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1Which book are you using to learn C++? This is a basic of the language, which should be explained in early chapters. – Lightness Races in Orbit Mar 18 '17 at 15:10
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@BoundaryImposition, good point. – Arash Mar 18 '17 at 15:36
1 Answers
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Class class("Test");
This object is on stack. It will be destroyed after the function it is in returns. Normally, stack allcation is faster than heap. But its size is limited (a few MBs, depends on compiler).
Class *class = new Class("Test");
This object is on heap. It should be deleteed by programmer after finish using. heap is useful for large objects (for example, if your variable is larger than the whole stack, it can only be allcated on heap), and memory reservation. Its size can be considered as the entire memory space.
zhm
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2Unless specifics are given it's better to stick with Automatic and Dynamic storage. Stack and Heap are by far the most common implementations of Automatic and Dynamic storage, but they aren't the only implementations and the C++ Standard is worded to allow any implementation that follows the defined rules. – user4581301 Mar 18 '17 at 15:05
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Worth an edit to note that Automatic and Dynamic allocations have different lifetime rules. – user4581301 Mar 18 '17 at 15:06
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1And I agree - don't propagate this confusing and outdated "stack vs heap" nonsense to a new generation please! – Lightness Races in Orbit Mar 18 '17 at 15:07
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