made it easier to change the stack test size, added linked-list imple…

…mentation by Eric

stack/Makefile

@@ -2,6 +2,6 @@ all:
 	@rm -rf build; mkdir -p build
 	cd build; cmake ../
 	cd build; make
-	./build/stack-test
+	valgrind ./build/stack-test
 
 .PHONY: all

stack/stack-test.c

@@ -10,6 +10,7 @@ void fail(char* msg) {
 }
 
 int main(int argc, char* argv[]) {
+  int max_len = 100;
   char* a = "abc";
   char* d = "def";
   char* g = "ghijklmnopqrstuvwxyz";
@@ -58,7 +59,7 @@ int main(int argc, char* argv[]) {
   // Test that stack can hold any number of elements
   //
   len = 1;
-  while (len < 99) {
+  while (len < (max_len - 1)) {
     len += 1;
 
     if (len != s_push(s, (void*) d)) {
@@ -78,11 +79,11 @@ int main(int argc, char* argv[]) {
   //
   // Test edge case of last element inserted and removed
   //
-  if (100 != s_push(s, (void*) g)) {
+  if (max_len != s_push(s, (void*) g)) {
     fail("stack length is not 100");
   }
 
-  if (100 != s_length(s)) {
+  if (max_len != s_length(s)) {
     fail("stack is not length 100 after adding 100 items");
   }
 
@@ -94,15 +95,15 @@ int main(int argc, char* argv[]) {
     fail("stack item 1 doesn't match peek");
   }
 
-  if (99 != s_length(s)) {
+  if ((max_len - 1) != s_length(s)) {
     fail("stack is not length 99 after removing 1 item");
   }
 
 
   //
   // Test that the stack can be emptied as it was filled
   //
-  len = 99;
+  len = max_len - 1;
   while (len > 1) {
     len -= 1;
 

stack/stack.reference.eric.c

@@ -0,0 +1,81 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
+*                               *
+*   Name:   Eric Jacobs                       *
+*   What:   Stack Implementation                      *
+*   Date:   Aug 16, 2011                        *
+*   File:   stack.c                       *
+*   Version:0.1                           *
+*                               *
+\* * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "include/stack.h"
+
+// the implementation of the stack
+struct Stack {
+  struct Node* top;
+  int length;
+};
+
+// Node for the linked list which will make the Stack.
+struct Node {
+  struct Node* prev;
+  void* v;
+};
+
+// Initialize a Node.
+struct Node* node_create(struct Node* prev, void* content);
+
+struct Node* node_create(struct Node* prev, void* v) {
+  struct Node* n = (struct Node*)malloc(sizeof(struct Node));
+  n->prev = prev;
+  n->v    = v;
+  return n;
+}
+
+struct Stack* s_create() {
+  struct Stack* s = (struct Stack*)malloc(sizeof(struct Stack));
+
+  s->top    = NULL;
+  s->length = 0;
+  return s;
+}
+
+int s_length(struct Stack* s) {
+  return s->length;
+}
+
+int s_push(struct Stack* s, void* v) {
+  struct Node* new_node = node_create(s->top, v);
+  s->top = new_node;
+  return ++s->length;
+}
+
+void* s_pop(struct Stack* s) {
+  if(s->top == NULL) {
+    return NULL;
+  }
+  struct Node* node_tbd = s->top;
+  void* v = node_tbd->v;
+  s->top = node_tbd->prev;
+  free(node_tbd);
+  node_tbd = NULL;
+  s->length--;
+  return v;
+}
+
+void* s_peek(struct Stack* s) {
+  if(s->top == NULL) {
+    return NULL;
+  }
+  return s->top->v;
+}
+
+void s_destroy(struct Stack* s) {
+  while(s->length > 0) {
+    s_pop(s);
+  }
+  free(s);
+  s = NULL;
+}