# fputc

## PROLOG



           This manual page is part of the POSIX Programmer's Manual.  The
           Linux implementation of this interface may differ (consult the
           corresponding Linux manual page for details of Linux behavior), or
           the interface may not be implemented on Linux.
    


## NAME



           fputc — put a byte on a stream
    


## SYNOPSIS



           #include <stdio.h>
    
           int fputc(int _c_ , FILE *_stream_);
    


## DESCRIPTION



           The functionality described on this reference page is aligned with
           the ISO C standard. Any conflict between the requirements
           described here and the ISO C standard is unintentional. This
           volume of POSIX.1‐2017 defers to the ISO C standard.
    
           The _fputc_() function shall write the byte specified by _c_
           (converted to an **unsigned char**) to the output stream pointed to by
           _stream_ , at the position indicated by the associated file-position
           indicator for the stream (if defined), and shall advance the
           indicator appropriately.  If the file cannot support positioning
           requests, or if the stream was opened with append mode, the byte
           shall be appended to the output stream.
    
           The last data modification and last file status change timestamps
           of the file shall be marked for update between the successful
           execution of _fputc_() and the next successful completion of a call
           to _fflush_() or _fclose_() on the same stream or a call to _exit_() or
           _abort_().
    


## RETURN VALUE



           Upon successful completion, _fputc_() shall return the value it has
           written. Otherwise, it shall return EOF, the error indicator for
           the stream shall be set, and _errno_ shall be set to indicate the
           error.
    


## ERRORS



           The _fputc_() function shall fail if either the _stream_ is unbuffered
           or the _stream_ 's buffer needs to be flushed, and:
    
           **EAGAIN** The O_NONBLOCK flag is set for the file descriptor
                  underlying _stream_ and the thread would be delayed in the
                  write operation.
    
           **EBADF** The file descriptor underlying _stream_ is not a valid file
                  descriptor open for writing.
    
           **EFBIG** An attempt was made to write to a file that exceeds the
                  maximum file size.
    
           **EFBIG** An attempt was made to write to a file that exceeds the
                  file size limit of the process.
    
           **EFBIG** The file is a regular file and an attempt was made to write
                  at or beyond the offset maximum.
    
           **EINTR** The write operation was terminated due to the receipt of a
                  signal, and no data was transferred.
    
           **EIO** A physical I/O error has occurred, or the process is a
                  member of a background process group attempting to write to
                  its controlling terminal, TOSTOP is set, the calling thread
                  is not blocking SIGTTOU, the process is not ignoring
                  SIGTTOU, and the process group of the process is orphaned.
                  This error may also be returned under implementation-
                  defined conditions.
    
           **ENOSPC** There was no free space remaining on the device containing
                  the file.
    
           **EPIPE** An attempt is made to write to a pipe or FIFO that is not
                  open for reading by any process. A SIGPIPE signal shall
                  also be sent to the thread.
    
           The _fputc_() function may fail if:
    
           **ENOMEM** Insufficient storage space is available.
    
           **ENXIO** A request was made of a nonexistent device, or the request
                  was outside the capabilities of the device.
    
           _The following sections are informative._
    


## EXAMPLES



           None.
    


## APPLICATION USAGE



           None.
    


## RATIONALE



           None.
    


## FUTURE DIRECTIONS



           None.
    


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