Open System Services Library Calls Reference Manual (G06.29+, H06.08+, J06.03+)

OSS Library Calls (e - f) fwrite(3)
NAME
fwrite - Writes to an output stream
LIBRARY
G-series native Guardian processes: $SYSTEM.SYSnn.ZCRTLSRL
G-series native OSS processes: /G/system/sysnn/zcrtlsrl
H-series and J-series native Guardian processes: $SYSTEM.ZDLLnnn.ZCRTLDLL
32-bit H-series and J-series OSS processes: /G/system/zdllnnn/zcrtldll
64-bit H-series and J-series OSS processes: /G/system/zdllnnn/ycrtldll
SYNOPSIS
#include <stdio.h>
size_t fwrite(
const void ∗∗pointer,
size_t size,
size_t num_items,
FILE ∗∗stream);
PARAMETERS
pointer Points to an array.
size Specifies the size of the variable type of the array pointed to by the pointer
parameter.
num_items Specifies the number of items of data.
stream Specifies the output stream.
DESCRIPTION
The fwrite( ) function appends num_items of data of length size from the array pointed to by the
pointer parameter to the output stream.
The fwrite( ) function stops writing bytes if an error condition is encountered on the stream, or
when the number of items of data specified by the num_items parameter have been written. The
fwrite( ) function does not change the contents of the array pointed to by the pointer parameter.
NOTES
If the stream parameter is invalid, the result of calling the fwrite( ) function is undefined.
RETURN VALUES
Upon successful completion, the fwrite( ) function returns the number of items actually
transferred. If the num_items parameter is negative or 0 (zero), no characters are transferred, and
a value of 0 (zero) is returned. If a write error occurs, the error indicator for the stream is set, and
errno is set to indicate the error.
ERRORS
The fwrite( ) function fails if:
• The stream parameter is not open for writing.
• The output file size cannot be increased.
• The stream is unbuffered.
• The stream’s buffer needed to be flushed and the function call caused an underlying
write( ) or lseek( ) to be invoked and this underlying operation fails.
In addition, if any of the following conditions occur, the fwrite( ) function sets errno to the
corresponding value:
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