How to Efficiently Read Files into std::vector Without Unnecessary Overhead?

Alternative Methods for Reading Files into std::vector

Reading files into std::vector efficiently is essential for data processing tasks. However, some methods, such as reserve() and resize(), incur additional overhead due to element initialization. For this reason, alternative methods may be preferred.

One such method is to leverage iterators from the std::istreambuf_iterator class. This approach eliminates unnecessary copies and allows for direct access to the file's contents. The canonical form of this approach is:

#include<iterator>
// ...

std::ifstream testFile("testfile", std::ios::binary);
std::vector<char> fileContents((std::istreambuf_iterator<char>(testFile)),
                               std::istreambuf_iterator<char>());

To prevent reallocations, consider reserving space in the vector beforehand:

#include<iterator>
// ...

std::ifstream testFile("testfile", std::ios::binary);
std::vector<char> fileContents;
fileContents.reserve(fileSize);
fileContents.assign(std::istreambuf_iterator<char>(testFile),
                    std::istreambuf_iterator<char>());

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