roll(1)

src/roll.c

@@ -0,0 +1,56 @@
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sysexits.h>
+#include <time.h>
+#include "libio.h"
+
+static char *program_name = "roll";
+
+int main(int argc, char *argv[]){
+	char *argv0;
+	char *argvc;
+	int r; /* rolls */
+	int s; /* sides */
+
+	argv0 = argv[0];
+
+	if(argc < 2){
+		fprintf(stderr,
+			"Usage: %s [dice...]\n"
+			"\tDice should be formatted [rolls]d[sides], e.g. 1d3, 5d6...\n",
+			argv0 == NULL? program_name : argv0
+		);
+	}
+
+	srand(time(NULL));
+
+	while(--argc > 0){
+		argvc = *++argv;
+
+		/* Parse out [rolls]d[sides] */
+		if(!isdigit(**argv)){
+error:			fprintf(stderr,
+				"%s: %s: Improperly formatted die (should be"
+				" [rolls]d[sides]).",
+				argv0, argvc
+			);
+			return EX_USAGE;
+		}
+		r = parse_uint(*argv);
+		while(isdigit(**argv))
+			++*argv;
+		if(*((*argv)++) != 'd' || !isdigit(**argv))
+			goto error;
+		s = parse_uint(*argv);
+		while(isdigit(**argv))
+			++*argv;
+		if(**argv != '\0')
+			goto error;
+
+		while(--r >= 0)
+			fdputd(1, rand() % s + 1);
+	}
+
+	return EX_OK;
+}