1 files changed, 88 insertions, 0 deletions
diff --git a/src/rij.c b/src/rij.c
new file mode 100644
index 0000000..1ea1b35
--- /dev/null
+++ b/src/rij.c
@@ -0,0 +1,88 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <limits.h>
+#include <unistd.h>
+#include <errno.h>
+#include "util/versie.h"
+
+
+static void usage(FILE *f) {
+  fprintf(f,
+      "Gebruik: rij [-hV] [EERSTE] [STAP] LAATSTE\n"
+      "\n"
+      "Druk getallen van EERSTE t/m LAATSTE af, in stappen van STAP.\n"
+      "\n"
+      "  -h    Toon deze hulptekst\n"
+      "  -V    Toon versienummer\n");
+}
+
+// Returns pointer to argument array containing the file names
+static char** parse_options(int argc, char **argv) {
+  int opt;
+  while ((opt = getopt(argc, argv, "hV")) != -1) {
+    switch (opt) {
+      case 'h':
+        usage(stdout);
+        exit(0);
+
+      case 'V':
+        drukkedoos_print_versie(stdout, "rij");
+        exit(0);
+
+      case '?':
+        fprintf(stderr, "Ongeldige optie: -%c\n", optopt);
+        usage(stderr);
+        exit(1);
+    }
+  }
+
+  return argv + optind;
+}
+
+int entry_rij(int argc, char **argv) {
+  char **args = parse_options(argc, argv);
+
+  // Use 'long long' because that's what strtoll() parses
+  long long argnums[3], nnums = 0;
+  while (*args && nnums < 3) {
+    char *endp;
+    errno = 0;
+    argnums[nnums++] = strtoll(*args, &endp, 10);
+    if (errno == ERANGE) {
+      fprintf(stderr, "rij: Getal te groot: %s\n", *args);
+      return 1;
+    }
+    if (!**args || *endp) {
+      fprintf(stderr, "rij: Ongeldig getal '%s'\n", *args);
+      return 1;
+    }
+    args++;
+  }
+
+  if (nnums == 0) {
+    fprintf(stderr, "rij: Missend argument\n");
+    return 1;
+  }
+
+  if (nnums == 3 && *args) {
+    fprintf(stderr, "rij: Teveel argumenten\n");
+    return 1;
+  }
+
+  long long start, step, end;
+  switch (nnums) {
+    case 1: start = step = 1; end = argnums[0]; break;
+    case 2: start = argnums[0]; step = 1; end = argnums[1]; break;
+    case 3: start = argnums[0]; step = argnums[1]; end = argnums[2]; break;
+  }
+
+  const long long safeend = end == LLONG_MAX ? LLONG_MAX - 1 : end;
+
+  for (long long i = start; i <= safeend; i += step) {
+    printf("%lld\n", i);
+  }
+
+  if (end == LLONG_MAX) printf("%lld\n", LLONG_MAX);
+
+  return 0;
+}