Working with the Unix OS

C Libraries
6. C LIBRARIES
Input and Output
I/O streams that point to a file are block buffered.
Streams that point to a terminal (stdin & stdout) are line buffered.
To explicitly direct the system to flush the buffer at any time use the function 'ff lush"
void setbuf(FILE *stream, char *buf)
If you pass a null pointer as the buffer, the stream is unbuffered.
header file – standard I/0 functions
- prototype declarations for all I/0 functions
- declaration of the FILE structure
- macros – stdin, stdout, stderr, EOF, NULL
getc()
fgetc(*fp++)
getchar()
putc()
fputc(c,*fp++)
putchar()
ferror() NULL is zero
clearerr() EOF is -1
feof()
/* stream_stat.c
if neither flag is set, stat will equal zero
if error is set, but not eof, stat equals 1
if eof is set, but not error, stat equals 2
if both flags are set, stat equals 3
*/
#include
#define EOF_FLAG 1
#define ERR_FLAG 2
char stream_stat(FILE *fp)
{
char stat=0;
if (ferror(fp))
stat |= ERR_FLAG;
if (feof(fp))
stat |= EOF_FLAG;
clearerr(fp);
return stat;
}
! More I/O info:
int getchar(void) = getc(stdin)
char *gets(char *string)= reads a line from stdin
/* gets = reads the linefeed & converts to a NULL */
int printf(char *format)
int putchar(char c) = putc(c, stdout)
int puts(char *string) = writes a line to stdout
int scanf(char *format)
File I/O
FILE *fopen(char *filename, char *type)
type | Description
"r" open existing text file for reading at beginning
"w" create a new text file for writing
"a" open an existing text file in append mode
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