Exercise 8.01

Page 174

Rewrite the program cat from Chapter 7 using read, write, open and close instead of their standard library equivalents. Perform experiments to determine the relative speeds of the two versions.

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

int main(int argc, char *argv[])
{
	FILE *fp;
	void filecopy(FILE *, FILE *);
	char *prog = argv[0];

	if (argc == 1) {
		filecopy(stdin, stdout);
	} else {
		while (--argc > 0) {
			if ((fp = fopen(*++argv, "r")) == NULL) {
				fprintf(stderr, "%s: can't open e%s\n", prog,
					*argv);
				exit(1);
			} else {
				filecopy(fp, stdout);
				fclose(fp);
			}
		}
	}
	if (ferror(stdout)) {
		fprintf(stderr, "%s: error writing stdout\n", prog);
		exit(2);
	}
	exit(0);
}

void filecopy(FILE *ifp, FILE *ofp)
{
	int c;

	while ((c = getc(ifp)) != EOF) {
		putc(c, ofp);
	}
}