Question

所以我设法创建了一个动态列表，目前我只能在每个节点中插入一个字符，可以删除一个节点并打印整个列表，但是尝试更改列表时遇到很多麻烦这样我就可以在每个节点中插入一个动态数组并将其打印到文件中，有人可以给我一些建议吗？

#include <stdio.h>
#include <stdlib.h>
// self-referential structure                       
struct listNode {                                      
   char * data; // each listNode contains a character 
   struct listNode *nextPtr; // pointer to next node
}; 
typedef struct listNode ListNode; // synonym for struct listNode
typedef ListNode *ListNodePtr; // synonym for ListNode*
// prototypes
void insert(ListNodePtr *sPtr, char value);
char delete(ListNodePtr *sPtr, char value);
int isEmpty(ListNodePtr sPtr);
void printList(ListNodePtr currentPtr);
void instructions(void);
int main(void)
{ 
   ListNodePtr startPtr = NULL; // initially there are no nodes
   char item; // char entered by user
   instructions(); // display the menu
   printf("%s", "? ");
   unsigned int choice; // user's choice
   scanf("%u", &choice);
   // loop while user does not choose 3
   while (choice != 3) { 
      switch (choice) { 
         case 1:
            printf("%s", "Enter a character: ");
            scanf("\n%c", &item);
            insert(&startPtr, item); // insert item in list
            printList(startPtr);
            break;
         case 2: // delete an element
            // if list is not empty
            if (!isEmpty(startPtr)) { 
               printf("%s", "Enter character to be deleted: ");
               scanf("\n%c", &item);
               // if character is found, remove it
               if (delete(&startPtr, item)) { // remove item
                  printf("%c deleted.\n", item);
                  printList(startPtr);
               } 
               else {
                  printf("%c not found.\n\n", item);
               } 
            } 
            else {
               puts("List is empty.\n");
            } 
            break;
         default:
            puts("Invalid choice.\n");
            instructions();
            break;
      } // end switch
      printf("%s", "? ");
      scanf("%u", &choice);
   } 
   puts("End of run.");
} 
// display program instructions to user
void instructions(void)
{ 
   puts("Enter your choice:\n"
      "   1 to insert an element into the list.\n"
      "   2 to delete an element from the list.\n"
      "   3 to end.");
} 
// insert a new value into the list in sorted order
void insert(ListNodePtr *sPtr, char value)
{ 
   ListNodePtr newPtr = malloc(sizeof(ListNode)); // create node
   if (newPtr != NULL) { // is space available
      newPtr->data = value; // place value in node
      newPtr->nextPtr = NULL; // node does not link to another node
      ListNodePtr previousPtr = NULL;
      ListNodePtr currentPtr = *sPtr;
      // loop to find the correct location in the list       
      while (currentPtr != NULL && value > currentPtr->data) {
         previousPtr = currentPtr; // walk to ...               
         currentPtr = currentPtr->nextPtr; // ... next node 
      }                                          
      // insert new node at beginning of list
      if (previousPtr == NULL) { 
         newPtr->nextPtr = *sPtr;
         *sPtr = newPtr;
      } 
      else { // insert new node between previousPtr and currentPtr
         previousPtr->nextPtr = newPtr;
         newPtr->nextPtr = currentPtr;
      } 
   } 
   else {
      printf("%c not inserted. No memory available.\n", value);
   } 
} 
// delete a list element
char delete(ListNodePtr *sPtr, char value)
{ 
   // delete first node if a match is found
   if (value == (*sPtr)->data) { 
      ListNodePtr tempPtr = *sPtr; // hold onto node being removed
      *sPtr = (*sPtr)->nextPtr; // de-thread the node
      free(tempPtr); // free the de-threaded node
      return value;
   } 
   else { 
      ListNodePtr previousPtr = *sPtr;
      ListNodePtr currentPtr = (*sPtr)->nextPtr;
      // loop to find the correct location in the list
      while (currentPtr != NULL && currentPtr->data != value) { 
         previousPtr = currentPtr; // walk to ...  
         currentPtr = currentPtr->nextPtr; // ... next node  
      } 
      // delete node at currentPtr
      if (currentPtr != NULL) { 
         ListNodePtr tempPtr = currentPtr;
         previousPtr->nextPtr = currentPtr->nextPtr;
         free(tempPtr);
         return value;
      } 
   } 
   return '\0';
} 
// return 1 if the list is empty, 0 otherwise
int isEmpty(ListNodePtr sPtr)
{ 
   return sPtr == NULL;
} 
// print the list
void printList(ListNodePtr currentPtr)
{ 
   // if list is empty
   if (isEmpty(currentPtr)) {
      puts("List is empty.\n");
   } 
   else { 
      puts("The list is:");
      // while not the end of the list
      while (currentPtr != NULL) { 
         printf("%c --> ", currentPtr->data);
         currentPtr = currentPtr->nextPtr;   
      } 
      puts("NULL\n");
   } 
}

Answer 1

您必须打开编译器警告。它会告诉您在哪里违反C的某些规则。例如，newPtr->data = value;应该抱怨，因为data是一个指针，而value是一个字符。

但是，您应该使用"%s"的{{1}}格式说明符向用户读取一个字符串，并将其放入足够大的缓冲区（或在读取时指定界限），例如缓冲区{{1 }}。

您将此缓冲区传递给scanf。您无需分配char strbuf[256];到insert，而是先分配一个新字符串，然后将值复制到新字符串：

value

（此答案排除了您的解决方案可能存在的任何其他错误或问题。）

如何将单词保存到动态列表中

1 个答案: