new file mode 100644

@@ -0,0 +1,70 @@

+#include <stdio.h>

+#include <stdlib.h>

+

+typedef unsigned int item_type;

+typedef struct list {

+  item_type item;

+  struct list * next;

+} list;

+

+list * search_list(list *l, item_type x) {

+  if (l == NULL) return NULL;

+

+  if (l->item == x) {

+    return l;

+  } else {

+    return search_list(l->next, x);

+  }

+}

+

+void insert_list(list **l, item_type x) {

+  list *p;

+

+  p = malloc(sizeof(list) );

+  p->item = x;

+  p->next = *l;

+  *l = p;

+}

+

+list *predecessor_list(list *l, item_type x) {

+  if ((l == NULL) || (l->next == NULL)) {

+    printf("Error: predecessor sought on null list.\n");

+    return NULL;

+  }

+

+  if ((l->next)->item == x) {

+    return l;

+  } else {

+    return predecessor_list(l->next, x);

+  }

+}

+

+delete_list(list **l, item_type x) {

+  list *p;

+  list * pred;

+

+  p = search_list(*l, x);

+  if (p != NULL) {

+    pred = predecessor_list(*l, x);

+    if (pred == NULL) {

+      *l = p->next;

+    } else {

+      pred->next = p->next;

+    }

+

+    free(p);

+  }

+}

+

+item_type i(list *l) {

+  if (l == NULL) return -1;

+  return l->item;

+}

+int main() {

+  list *l = NULL;

+  insert_list(&l, 123);

+  insert_list(&l, 234);

+  delete_list(&l, 123);

+  printf("%u\n", i(search_list(l, 123)));

+  return 42;

+}