How to Efficiently Read a Binary File into a Vector of Unsigned Chars?

Alternative Ways to Read a Binary File into a Vector of Unsigned Chars

Your provided function for reading a binary file into a vector of unsigned chars is a viable option, but it could be simplified.

Using std::istreambuf_iterator

The std::istreambuf_iterator approach is concise but assumes the use of std::istreambuf_iterator even when reading into a vector of unsigned chars.

Using std::basic_ifstream

The std::basic_ifstream approach explicitly indicates the intention of reading BYTEs, but it's unclear whether this is the most appropriate choice.

Other Options

An alternative approach that avoids the explicit cast to char* is:

<code class="cpp">std::vector<byte> readFile(const char* filename)
{
    std::ifstream file(filename, std::ios::binary);
    file.unsetf(std::ios::skipws); // Prevent skipping newlines in binary mode
    std::streampos fileSize = file.tellg();
    file.seekg(0, std::ios::beg);

    std::vector<byte> fileData;
    fileData.reserve(fileSize);
    fileData.insert(fileData.begin(),
                     std::istream_iterator<byte>(file),
                     std::istream_iterator<byte>());
    return fileData;
}</byte></byte></byte></byte></code>

This method reserves the necessary capacity in the vector before inserting the data, potentially eliminating the need for costly resizes.

Directly Copying Binary Data

A more efficient approach would be to directly copy the binary data into the vector without using an iterator. However, this requires a platform-specific implementation that depends on the underlying file I/O library.

Performance Considerations

When comparing performance, consider testing large binary files to assess the impact of vector resizes and the overhead of different approaches.

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