fdopenfdint

fdopenfdint is a function in the C programming language that is part of the POSIX standard. It is used to associate a C stream with an existing file descriptor. A file descriptor is a low-level integer handle to an open file or other I/O resource. The `fdopen` function takes an integer file descriptor and a string mode (similar to `fopen`) as arguments. It returns a pointer to a `FILE` structure, which can then be used with standard C I/O functions like `fread`, `fwrite`, `fprintf`, and `fscanf`. This allows programmers to use the convenience of buffered, high-level C I/O on resources that were initially opened using lower-level system calls that return file descriptors, such as `open` or `socket`. The `fdopen` function essentially wraps the file descriptor in a C standard I/O stream. It's important to note that when the C stream returned by `fdopen` is closed using `fclose`, the underlying file descriptor is also closed. This behavior can be significant and requires careful management to avoid double-closing file descriptors if they are managed elsewhere. `fdopen` is commonly used in scenarios where a program needs to interoperate with libraries or system calls that provide file descriptors, but the program prefers to use standard C streams for subsequent data manipulation.