How Can I Obtain a FILE* Handle from a C std::fstream Object?

Retrieving a FILE* Handle from a std::fstream

In the realm of C programming, it may arise that you seek to utilize a C function that necessitates a FILE handle. However, the standard C library provides the std::fstream class for file input and output. Therefore, a question arises: is there a cross-platform approach to derive a FILE handle from an existing std::fstream object?

The Limitations

Regrettably, the answer is in the negative. The std::fstream class is not obligated to employ a FILE* internally. Even if you were to successfully extract the underlying file descriptor from the std::fstream and manually construct a FILE object, it would subsequently lead to complications due to multiple buffered objects attempting to write to the same file descriptor.

Alternative Considerations

Instead of pursuing the conversion to a FILE*, it is worthwhile to question your reasons behind seeking this conversion. Are there other methods to accomplish your desired functionality without this specific requirement?

Potential Approach (Not Recommended)

If, for whatever reason, the conversion is still deemed essential, you may consider exploring funopen(). However, note that this approach is not a POSIX API and its portability across different operating systems is uncertain. Additionally, the implementation of funopen() varies across platforms.

The above is the detailed content of How Can I Obtain a FILE* Handle from a C std::fstream Object?. For more information, please follow other related articles on the PHP Chinese website!