fwrite(3c) [sunos man page]
fwrite(3C) Standard C Library Functions fwrite(3C) NAME
fwrite - binary output SYNOPSIS
#include <stdio.h> size_t fwrite(const void *ptr, size_t size, size_t nitems, FILE *stream); DESCRIPTION
The fwrite() function writes, from the array pointed to by ptr, up to nitems elements whose size is specified by size, to the stream pointed to by stream. For each object, size calls are made to the fputc(3C) function, taking the values (in order) from an array of unsigned char exactly overlaying the object. The file-position indicator for the stream (if defined) is advanced by the number of bytes successfully written. If an error occurs, the resulting value of the file-position indicator for the stream is unspecified. The st_ctime and st_mtime fields of the file will be marked for update between the successful execution of fwrite() and the next successful completion of a call to fflush(3C) or fclose(3C) on the same stream or a call to exit(2) or abort(3C). RETURN VALUES
The fwrite() function returns the number of elements successfully written, which might be less than nitems if a write error is encountered. If size or nitems is 0, fwrite() returns 0 and the state of the stream remains unchanged. Otherwise, if a write error occurs, the error indicator for the stream is set and errno is set to indicate the error. ERRORS
Refer to fputc(3C). USAGE
Because of possible differences in element length and byte ordering, files written using fwrite() are application-dependent, and possibly cannot be read using fread(3C) by a different application or by the same application on a different processor. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
write(2), fclose(3C), ferror(3C), fopen(3C), fread(3C), getc(3C), gets(3C), printf(3C), putc(3C), puts(3C), attributes(5), standards(5) SunOS 5.10 24 Jul 2002 fwrite(3C)
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fread(3) Library Functions Manual fread(3) NAME
fread, fread_unlocked, fwrite, fwrite_unlocked - Perform input/output operations LIBRARY
Standard C Library (libc.so, libc.a) SYNOPSIS
#include <stdio.h> size_t fread( void *pointer, size_t size, size_t num_items, FILE *stream); size_t fread_unlocked( void *pointer, size_t size, size_t num_items, FILE *stream); size_t fwrite( const void *pointer, size_t size, size_t num_items, FILE *stream); size_t fwrite_unlocked( const void *pointer, size_t size, size_t num_items, FILE *stream); STANDARDS
Interfaces documented on this reference page conform to industry standards as follows: fread(), fwrite(): XPG4, XPG4-UNIX Refer to the standards(5) reference page for more information about industry standards and associated tags. PARAMETERS
Points to an array. Specifies the size of the variable type of the array pointed to by the pointer parameter. Specifies the number of items of data. Specifies the input or output stream. DESCRIPTION
The fread() function copies num_items of data of length size from the input stream into an array beginning at the location pointed to by the pointer parameter. The fread() function stops copying bytes if an End-of-File or error condition is encountered while reading from the input specified by the stream parameter, or when the number of data items specified by the num_items parameter have been copied. The function leaves the file pointer of the stream parameter, if defined, pointing to the byte following the last byte read, if there is one. The fread() function does not change the contents of the stream parameter. 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. The fread_unlocked() and fwrite_unlocked() functions are functionally identical to the fread() and fwrite() functions, except that fread_unlocked() and fwrite_unlocked() may be safely used only within a scope that is protected by the flockfile() and funlockfile() func- tions used as a pair. The caller must ensure that the stream is locked before using these functions. NOTES
If the stream parameter is invalid, the result of calling the fread(), fwrite(), fread_unlocked(), and fwrite_unlocked() functions is unde- fined. RETURN VALUES
Upon successful completion, the fread(), fwrite(), fread_unlocked(), and fwrite_unlocked() functions return 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 read or write error occurs, the error indicator for the stream is set, and errno is set to indicate the error. ERRORS
Refer to the fgetc(3) reference page for error codes returned by fread() and fread_unlocked(). Refer to the fputc(3) reference page for error codes returned by fwrite() and fwrite_unlocked(). RELATED INFORMATION
Functions: read(2), write(2), fopen(3), getc(3), gets(3), printf(3), putc(3), puts(3), scanf(3) Standards: standards(5) delim off fread(3)