Thread: unix fold utility

Originally Posted by MK27

I believe this to be a foolproof and completely optimized way of parsing your particular options:

Code:

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

void wrong () {
	puts("Usage: fold [-s] [-w width] file ...");
	exit (-2);
}

int parse_w (char *arg) {
	int i, retv;
	if (sscanf(arg,"%d",&retv)!=1) wrong();
	return retv;	
}

int main (int argc, char *argv[]) {
	int i, len, sflag=0, width=80;
	FILE *fstRO;
	for (i=1;i<argc;i++) {
		if (strcmp(argv[i],"-s")==0) {sflag=1;continue;}
		if (strncmp(argv[i],"-w",2)==0) {
			if (strlen(argv[i])>2) {
				if (sscanf(argv[i], "-w%d",&width)!=1) wrong();
				continue;}
			else if (i==argc-1) wrong();
			width=parse_w(argv[i+1]);
			i++; continue;
		}
		break;
	}
	if (!(fstRO=fopen(argv[i],"r"))) {
		puts("File not openable");
		return -1;}
	printf("%s opened read-only\n",argv[i]);
	if (sflag==1) puts("-s set");
	printf("width set to %d\n",width);
	fclose(fstRO);
	return 0;
}

edit: except it doesn't parse the filename...oh well
edit2: okay now it does

what is int retv in the top function?

If I try to use this as a guide, i'll be pretty lost.

parse_w makes sure the value passed to it is an integer, and returns that integer if so. retv is the integer variable into which the string argument is parsed and which is returned to the caller.

Originally Posted by MK27

Why? I'm not a computer science prof yet, but it seems like something where you should be able to spot the angles after a few months. I wouldn't want my students to just sleep thru their final project -- I'd have such a big hat they'd love me forever

With a big hat you would even be able to pull off a bunny which is in contrast to what a teacher ought to do; perhaps a pointer or a nudge in the right direction. I was curious if something similar had been covered in class. However I would go with something along the lines that tabstop suggested or look at the man page of getopt() to get an idea of how to go about this.

All I have to say is :

http://www.conestogac.on.ca/registra...dishonesty.jsp

Do your assignments yourself. First year is NOTHING compared to the stuff to come. If you're having THAT much trouble I would consider switching to another program because it doesn't get any easier.