Does `std::vector::resize()` and `boost::container::vector::resize()` Exhibit Consistent Zero-Initialization Behavior Across C Standards?

Is Vector::resize() Behavior Consistent Under C 11 and Boost.Container?

The behavior of std::vector::resize() is commonly used for temporarily buffering data, resizing them to the appropriate size before use. In C 03, std::vector::resize() created new elements by copying, but C 11 introduced an overload that initializes new elements without copying.

Boost.Container provides an additional default_init overload for boost::container::vector::resize(), which initializes new elements with default values. This feature aligns with C 11's design philosophy of only paying for what you need.

Upon testing the behavior of std::vector and boost::container::vector under both C 03 and C 11 modes, unexpected results were observed. In both C 03 and C 11, resizing the vector without specifying initialization still resulted in zero initialization of new elements for both std::vector and boost::container::vector.

This behavior indicates that the interface change in std::vector has no effect on the implementation, and the final elements added in resize() are still initialized with zeros. The issue raised is whether this behavior is correct.

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