How Can I Reduce the Capacity of a std::vector Efficiently in C ?

Reducing the Capacity of a std::vector

When working with vectors, it is often helpful to reduce their capacity once they have reached a stable size. This can free up memory and improve performance for subsequent read operations.

Problem Statement:

Is there a way to reduce the capacity of a vector, excluding unnecessary copy operations and non-portable solutions?

Solution:

Yes, with C 11, you can utilize the shrink_to_fit() member function:

std::vector<int> myVector;
myVector.shrink_to_fit();

The shrink_to_fit() function reduces the capacity of the vector to match its current size. According to the C 11 draft standard:

shrink_to_fit is a non-binding request to reduce capacity() to size().

This request is non-binding to allow for implementation-specific optimizations. In practice, this means that calling shrink_to_fit() does not guarantee that the capacity will be reduced. However, it is a useful tool for reducing memory allocation and improving performance for read operations.

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