bufstat.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

void pr_stdio(const char *, FILE *);

int main(void)
{
	FILE	*fp;
	fputs("enter any character\n", stdout);
	if(getchar() == EOF)
	{
		perror("getchar error");
	}

	fputs("one line to standard error\n", stderr);

	pr_stdio("stdin", stdin);
	pr_stdio("stdout", stdout);
	pr_stdio("stderr", stderr);

	if((fp = fopen("/etc/motd", "r")) == NULL)
	{
		printf("fopen error");
	}

	if(getc(fp) == EOF)
	{
		perror("getc error");
	}

	pr_stdio("/etc/motd", fp);
	exit(0);
}

void pr_stdio(const char *name, FILE *fp)
{
	printf("stream = %s, ", name);
	
	if(fp->_IO_file_flags & _IO_UNBUFFERED)
		printf("unbuffered");
	
	else if(fp->_IO_file_flags & _IO_LINE_BUF)
		printf("line buffered");
	else
		printf("fully buffered");

	printf(", buffer size = %d\n", fp->_IO_buf_end - fp->_IO_buf_base);
}