From b15e1ad79474efff05f1d82c8a6744df3b1276c7 Mon Sep 17 00:00:00 2001
From: Dan Buch <daniel.buch@gmail.com>
Date: Wed, 13 Apr 2016 11:14:31 -0400
Subject: [PATCH] Goofing around with a naive stack impl

---
 lcthw-remnants-2/.gitignore |  1 +
 lcthw-remnants-2/ex17-ec2.c | 86 +++++++++++++++++++++++++++++++++++++
 2 files changed, 87 insertions(+)
 create mode 100644 lcthw-remnants-2/ex17-ec2.c

diff --git a/lcthw-remnants-2/.gitignore b/lcthw-remnants-2/.gitignore
index 8072b4b..976020d 100644
--- a/lcthw-remnants-2/.gitignore
+++ b/lcthw-remnants-2/.gitignore
@@ -17,3 +17,4 @@ ex16
 ex17
 db.dat
 ex17-ec
+ex17-ec2
diff --git a/lcthw-remnants-2/ex17-ec2.c b/lcthw-remnants-2/ex17-ec2.c
new file mode 100644
index 0000000..58a7f02
--- /dev/null
+++ b/lcthw-remnants-2/ex17-ec2.c
@@ -0,0 +1,86 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#define MAX_STACK 1024
+#define STACK_SENTINEL -1
+
+struct Stack {
+  int l[MAX_STACK];
+};
+
+struct Stack *Stack_create()
+{
+  struct Stack *s = malloc(sizeof(struct Stack));
+  if(!s) { return NULL; }
+
+  int i = 0;
+
+  for(i = 0; i < MAX_STACK; i++) {
+    s->l[i] = STACK_SENTINEL;
+  }
+
+  return s;
+}
+
+int Stack_push(struct Stack *s, int v)
+{
+  if(v <= STACK_SENTINEL) {
+    return STACK_SENTINEL;
+  }
+
+  int i = 0;
+  for(i = 0; i < MAX_STACK; i++) {
+    if(s->l[i] == STACK_SENTINEL) {
+      s->l[i] = v;
+      return i;
+    }
+  }
+
+  return STACK_SENTINEL;
+}
+
+int Stack_pop(struct Stack *s)
+{
+  int i = 0;
+  int v = 0;
+  for(i = 0; i < MAX_STACK; i++) {
+    if(s->l[i] == STACK_SENTINEL) {
+      v = s->l[i-1];
+      s->l[i-1] = STACK_SENTINEL;
+      return v;
+    }
+  }
+
+  return STACK_SENTINEL;
+}
+
+int Stack_size(struct Stack *s)
+{
+  int i = 0;
+  for(i = 0; i < MAX_STACK; i++) {
+    if(s->l[i] == STACK_SENTINEL) {
+      return i;
+    }
+  }
+
+  return STACK_SENTINEL;
+}
+
+int main(int argc, char *argv[])
+{
+  struct Stack *s = Stack_create();
+
+  printf("size: %d\n", Stack_size(s));
+  Stack_push(s, 10);
+  Stack_push(s, 20);
+  Stack_push(s, 40);
+
+  printf("size: %d\n", Stack_size(s));
+  printf("pop: %d\n", Stack_pop(s));
+  printf("pop: %d\n", Stack_pop(s));
+  printf("size: %d\n", Stack_size(s));
+  printf("pop: %d\n", Stack_pop(s));
+  printf("pop: %d\n", Stack_pop(s));
+
+  return 0;
+}