From ac55496d881e0a17b3eff85f1faae5aafbc53b50 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Wed, 22 Jul 2020 17:30:45 +0200
Subject: erster Commit

---
 stack2.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 stack2.c

(limited to 'stack2.c')

diff --git a/stack2.c b/stack2.c
new file mode 100644
index 0000000..57dce4f
--- /dev/null
+++ b/stack2.c
@@ -0,0 +1,100 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+#include "util.h"
+
+typedef int T;
+
+struct stack {
+	T *array;
+	size_t sz, p;
+};
+
+void
+stack_init(struct stack *stack)
+{
+	stack->array = NULL;
+	stack->sz = 0;
+	stack->p = 0;
+}
+
+bool
+stack_push(struct stack *stack, T data)
+{
+	if ( stack->array == NULL ) {
+		if ( (stack->array = malloc(10 * sizeof(*stack->array))) != NULL ) {
+			stack->sz = 10;
+			stack->p = 0;
+		}
+		else {
+			ERROR("out of memory");
+			return false;
+		}
+	}
+
+	if ( stack->p == stack->sz ) {
+		size_t new_sz;
+		T *new_array;
+
+	   	if ( (new_array = realloc(stack->array, (new_sz = (stack->sz * 3 / 2)) * sizeof(*stack->array))) != NULL ) {
+			stack->array = new_array;
+			stack->sz = new_sz;
+		}
+		else {
+			ERROR("out of memory");
+			return false;
+		}
+	}
+
+	stack->array[stack->p++] = data;
+	return true;
+}
+
+bool
+stack_pop(struct stack *stack, T *data)
+{
+	if ( stack->p != 0 ) {
+		*data = stack->array[--stack->p];
+		return true;
+	}
+	else
+		return false;
+}
+
+bool
+stack_empty(struct stack *stack)
+{
+	return stack->p == 0;
+}
+
+void
+stack_free(struct stack *stack)
+{
+	free(stack->array);
+}
+
+int
+main()
+{
+	struct stack stack[1];
+
+	stack_init(stack);
+
+	for ( int i = 0; i != 20; ++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;
+}
+
-- 
cgit v1.3