Created
June 18, 2017 05:30
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std::vector resizing with copies?
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| #include <iostream> | |
| #include <vector> | |
| struct Foo { | |
| Foo() { } | |
| Foo(const Foo &x) { | |
| std::cout << "Copied!" << std::endl; | |
| } | |
| Foo(Foo &&x) { | |
| std::cout << "Moved!" << std::endl; | |
| } | |
| }; | |
| int main() { | |
| auto vec = std::vector<Foo>(); | |
| for (int i=0; i<10; i++) { | |
| std::cout << "Capacity: " << vec.capacity() << std::endl; | |
| vec.push_back(Foo()); | |
| } | |
| return 0; | |
| }>> |
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| $ g++ -Wall -Werror -o foo foo.cc --std=c++14 && ./foo | |
| Capacity: 0 | |
| Moved! | |
| Capacity: 1 | |
| Moved! | |
| Copied! | |
| Capacity: 2 | |
| Moved! | |
| Copied! | |
| Copied! | |
| Capacity: 4 | |
| Moved! | |
| Capacity: 4 | |
| Moved! | |
| Copied! | |
| Copied! | |
| Copied! | |
| Copied! | |
| Capacity: 8 | |
| Moved! | |
| Capacity: 8 | |
| Moved! | |
| Capacity: 8 | |
| Moved! | |
| Capacity: 8 | |
| Moved! | |
| Copied! | |
| Copied! | |
| Copied! | |
| Copied! | |
| Copied! | |
| Copied! | |
| Copied! | |
| Copied! | |
| Capacity: 16 | |
| Moved! |
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