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More about temporary objects

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Geoff Liu 2015-08-30 14:41:02 -06:00
parent eb7e58d5fc
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@ -765,6 +765,22 @@ Foo f1 = fooSub;
Foo f1; Foo f1;
f1 = f2; f1 = f2;
// How to truly clear a container:
class Foo { ... };
vector<Foo> v;
for (int i = 0; i < 10; ++i)
v.push_back(Foo());
// Following line sets size of v to 0, but destructors don't get called,
// and resources aren't released!
v.empty();
v.push_back(Foo()); // New value is copied into the first Foo we inserted in the loop.
// Truly destroys all values in v. See section about temporary object for
// explanation of why this works.
v.swap(vector<Foo>());
``` ```
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