moitié tp 3

prepa_CM3/ex3_A/stack.c

@@ -0,0 +1,60 @@
+#include <stdlib.h>
+#include "stack.h"
+
+struct s_link {
+  unsigned value;
+  struct s_link *next;
+};
+
+typedef struct s_link link;
+
+struct s_stack {
+  link *first;
+};
+
+
+/* crée une pile vide */
+stack create_stack(void) {
+  return (stack) calloc(1, sizeof(struct s_stack));
+}
+
+/* ajoute un élément à la pile. Renvoie 1 en cas de succès */
+int push(stack the_stack, unsigned the_value) {
+  link *new = (link*) malloc(sizeof(link));
+  if (new == NULL) {
+    return 0;
+  }
+  new->value = the_value;
+  new->next = the_stack->first;
+  the_stack->first = new;
+  return 1;
+}
+
+/* renvoie 1 si la pile est vide */
+int empty(stack the_stack) {
+  return the_stack->first == NULL;
+}
+
+/* retire un élément de la pile. Renvoie l'élément retiré, ou -1 en cas d'échec */
+long pop(stack the_stack) {
+  if(the_stack->first == NULL) {
+    return -1;
+  }
+  link l = *(the_stack->first);
+  free(the_stack->first);
+  the_stack->first = l.next;
+  return l.value;
+}
+
+/* détruit une pile en libérant les ressources associées */
+void destroy_stack(stack the_stack) {
+  link *current, *saved;
+
+  current = the_stack->first;
+  while(current != NULL) {
+    saved = current->next;
+    free(current);
+    current = saved;
+  }
+  free(the_stack);
+}