Function Categories

I/O Functions

The SAS/C library provides a large set of input/output functions. These functions are divided into two groups, standard I/O functions and UNIX style I/O functions.

The library's I/O implementation is designed to

support the ISO/ANSI C standard
support the execution of existing programs developed with other C implementations
support the development of new portable programs
support the effective use of native OS/390 and CMS I/O facilities and file types.

The library provides several I/O techniques to meet the needs of different applications. To achieve the best results, you must make an informed choice about the techniques to use. Criteria that should influence your choice are

the need for portability (For example, will the program execute on several different systems?)
the required capabilities (For example, will the program need to alter the file position randomly during processing?)
the need for efficiency (For example, can the program accept some restrictions on file format to achieve good performance?)
the intended use of the files (For example, will files produced by the program later be processed by an editor or by a program written in another language?).

To make these choices, you need to understand general C I/O concepts as well as the native I/O types and file structures supported by the 370 operating systems, OS/390 and CMS.

Details about C I/O concepts and functions can be found in I/O Functions.

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`afflush`	flush file buffers to disk
`afopen`	open a file with system-dependent options
`afread`	read a record
`afread0`	read a record (possibly length zero)
`afreadh`	read part of a record
`afreopen`	reopen a file with system-dependent options
`afwrite`	write a record
`afwrite0`	write a record (possibly length 0)
`afwriteh`	write part of a record
`aopen`	open a file for UNIX style access with amparms
`clearerr`	clear error flag
`close`	close a file opened by `open`
`_close`	close an HFS file
`closedir`	close a directory
`clrerr`	clear error flag and return status
`creat`	create and open a file for UNIX style I/O
`ctermid`	get a filename for the terminal
`dup`	duplicate a file descriptor
`dup2`	duplicate a file descriptor to a specific file descriptor number
`fattr`	return file attribute information
`fclose`	close a file
`fcntl`	control open files or sockets
`_fcntl`	control open file descriptors for UNIX System Services (USS) HFS files
`fdopen`	access an USS file descriptor via standard I/O
`feof`	test for end of file
`ferror`	test error flag
`ffixed`	test for fixed-length records
`fflush`	flush output buffer
`fgetc`	read a character from a file
`fgetpos`	store the current file position
`fgets`	read a string from a file
`fileno`	return file descriptor number
`fnm`	return filename
`fopen`	open a file
`fprintf`	write formatted output to a file
`fputc`	write a character to a file
`fputs`	write a string to a file
`fread`	read items from a file
`freopen`	reopen a file
`fscanf`	read formatted input from a file
`fseek`	reposition a file
`fsetpos`	reposition a file
`fsync`	flush buffers for a UNIX style file to disk
`_fsync`	flush HFS file buffers to disk
`ftell`	obtain the current file position
`fterm`	terminal file test
`ftruncate`	truncate an USS file
`fwrite`	write items to a file
`getc`	read a character from a file
`getchar`	read a character from the standard input stream
`gets`	read a string from the standard input stream
`isatty`	test for terminal file
`kdelete`	delete current record from keyed file
`kgetpos`	return position information for keyed file
`kinsert`	insert record into keyed file
`kreplace`	replace record in keyed file
`kretrv`	retrieve next record from keyed file
`ksearch`	search keyed file for matching record
`kseek`	reposition a keyed stream
`ktell`	return RBA of current record
`lseek`	position a file opened for UNIX style access
`_lseek`	position an USS HFS file
`open`	open a file for UNIX style I/O
`_open`	open an USS HFS file
`opendir`	open an USS HFS directory
`pclose`	close a pipe opened by `popen`
`pipe`	create and open a pipe
`popen`	open pipe I/O to an USS shell command
`printf`	write formatted output to the standard output stream
`putc`	write a character to a file
`putchar`	write a character to the standard output stream
`puts`	write a string to the standard output stream
`read`	read data from a file opened for UNIX style access
`_read`	read data from an USS HFS file
`readdir`	read an USS directory entry
`rewind`	position to start of file
`rewinddir`	positions an USS directory stream to the beginning
`scanf`	read formatted data from the standard input stream
`setbuf`	change stream buffering
`setvbuf`	change stream buffering
`snprintf`	write a limited amount of formatted output to a string
`sprintf`	write formatted output to a string
`sscanf`	read formatted data from a string
`tmpfile`	create and open a temporary file
`tmpnam`	generate temporary filename
`ttyname`	get name of open terminal file
`ungetc`	push back an input character
`vfprintf`	write formatted output to a file
`vprintf`	write formatted output to the standard output stream
`vsnprintf`	write a limited amount of formatted output to a string
`vsprintf`	write formatted output to a string
`write`	write data to a file open for UNIX-style access
`_write`	write data to an USS HFS file.