fgetwc - get a wide-character code from a stream
#include <stdio.h> #include <wchar.h> wint_t fgetwc(FILE *stream);
The fgetwc() function obtains the next character (if present) from the input stream pointed to by stream, converts that to the corresponding wide-character code and advances the associated file position indicator for the stream (if defined).
If an error occurs, the resulting value of the file position indicator for the stream is indeterminate.
The fgetwc() function may mark the st_atime field of the file associated with stream for update. The st_atime field will be marked for update by the first successful execution of fgetc(), fgets(), fgetwc(), fgetws(), fread(), fscanf(), getc(), getchar(), gets() or scanf() using stream that returns data not supplied by a prior call to ungetc() or ungetwc().
Upon successful completion the fgetwc() function returns the wide-character code of the character read from the input stream pointed to by stream converted to a type wint_t. If the stream is at end-of-file, the end-of-file indicator for the stream is set and fgetwc() returns WEOF. If a read error occurs, the error indicator for the stream is set, fgetwc() returns WEOF and sets errno to indicate the error.
The fgetwc() function will fail if data needs to be read and:
- The O_NONBLOCK flag is set for the file descriptor underlying stream and the process would be delayed in the fgetwc() operation.
- The file descriptor underlying stream is not a valid file descriptor open for reading.
- The read operation was terminated due to the receipt of a signal, and no data was transferred.
- A physical I/O error has occurred, or the process is in a background process group attempting to read from its controlling terminal, and either the process is ignoring or blocking the SIGTTIN signal or the process group is orphaned. This error may also be generated for implementation-dependent reasons.
- The file is a regular file and an attempt was made to read at or beyond the offset maximum associated with the corresponding stream.
The fgetwc() function may fail if:
- Insufficient storage space is available.
- A request was made of a non-existent device, or the request was outside the capabilities of the device.
- The data obtained from the input stream does not form a valid character.
The ferror() or feof() functions must be used to distinguish between an error condition and an end-of-file condition.
feof(), ferror(), fopen(), <stdio.h>, <wchar.h>.
Derived from the MSE working draft.