erster Commit

1 files changed, 98 insertions, 0 deletions

diff --git a/stack.c b/stack.c
new file mode 100644
index 0000000..fa89974
--- /dev/null
+++ b/stack.c
@@ -0,0 +1,98 @@
+/* Standard C */
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+/* Project */
+#include "util.h"
+
+typedef int T;
+
+struct stack_item {
+        struct stack_item *next;
+        T data;
+};
+
+struct stack {
+        struct stack_item *head;
+};
+
+void
+stack_init(struct stack *stack)
+{
+        stack->head = NULL;
+}
+
+void
+stack_push(struct stack *stack, T data)
+{
+        struct stack_item *new_item;
+
+        if ( (new_item = malloc(sizeof(*new_item))) != NULL ) {
+                new_item->data = data;
+                new_item->next = stack->head;
+                stack->head = new_item;
+        }
+        else
+                ERROR("out of memory");
+}
+
+bool
+stack_pop(struct stack *stack, T *data)
+{
+        if ( stack->head != NULL ) {
+                struct stack_item *next = stack->head->next;
+                *data = stack->head->data;
+                free(stack->head);
+                stack->head = next;
+
+                return true;
+        }
+        else
+                return false;
+}
+
+bool
+stack_empty(struct stack *stack)
+{
+        return stack->head == NULL;
+}
+
+void
+stack_free(struct stack *stack)
+{
+        struct stack_item *item, *next;
+
+        for ( item = stack->head; item; item = next ) {
+                next = item->next;
+                free(item);
+        }
+}
+
+int
+main()
+{
+        struct stack stack[1];
+
+        stack_init(stack);
+
+        for ( int i = 0; i != 10; ++i )
+                stack_push(stack, i);
+
+        /*
+        while ( !stack_empty(stack) ) {
+                int i;
+                if ( stack_pop(stack, &i) )
+                        printf("%d\n", i);
+                else
+                        ERROR("this shouldn't happen!");
+        }
+        */
+
+        stack_free(stack);
+
+        return EXIT_SUCCESS;
+}
+
+
+