c - 程序中的未知错误

Question

我是C语言的新手，来自Java背景，调试这些函数时遇到了麻烦。基本上，他们的想法是传递一个单词，为链接列表创建一个节点，然后将新节点排序插入到链接列表中。我不明白我的错误在代码中，并且我在寻找如何解决它们方面遇到困难。如果有人可以帮助引导我走上正确的道路，我将非常感谢您的帮助!谢谢大家!请在下面找到我的函数的代码。

#include  <stdio.h>
#include <string.h>
//Node record
struct node {
char data;
struct node* next;
}; 



//insertion sorting (will sort as inserted)
void insert_dictionary_order(struct node** head_ref, char word)
{ 
   struct node* temp; 
   struct node* new_node; 
       new_node->data = word; 
       
   //If new insert is before head, put current head next, and set head to new node
   if (*head_ref == NULL || strcmp((*head_ref)->data, new_node->data) > 0)  //if new_node comes before this 
   {
       new_node->next=*head_ref; 
       *head_ref = new_node;
   } 
   else
   { 
       //find the node before insertion point 
       temp = *head_ref; 
       while(current->next != NULL && current->next->data < new_node->data) 
       { 
            current = current->next;
       } 
       new_node->next = next; 
       current->next = new_node;
   }
    
}



//function to print list by being passed head
void print_list(struct node *head) 
{ 
    Struct node *temp = head; 
    while(temp != NULL) 
    { 
        printf("%s\n", temp->data); 
        temp = temp->next;
    }
}

这是我收到的错误:

17899186/source.c: In function ‘insert_dictionary_order’:
17899186/source.c:21:36: warning: passing argument 1 of ‘strcmp’ makes pointer from integer without a cast [-Wint-conversion]
    if (*head_ref == NULL || strcmp((*head_ref)->data, new_node->data) > 0)  //if new_node comes before this
                                    ^
In file included from 17899186/source.c:4:0:
/usr/include/string.h:136:12: note: expected ‘const char *’ but argument is of type ‘char’
 extern int strcmp (const char *__s1, const char *__s2)
            ^~~~~~
17899186/source.c:21:55: warning: passing argument 2 of ‘strcmp’ makes pointer from integer without a cast [-Wint-conversion]
    if (*head_ref == NULL || strcmp((*head_ref)->data, new_node->data) > 0)  //if new_node comes before this
                                                       ^~~~~~~~
In file included from 17899186/source.c:4:0:
/usr/include/string.h:136:12: note: expected ‘const char *’ but argument is of type ‘char’
 extern int strcmp (const char *__s1, const char *__s2)
            ^~~~~~
17899186/source.c:30:14: error: ‘current’ undeclared (first use in this function)
        while(current->next != NULL && current->next->data < new_node->data)
              ^~~~~~~
17899186/source.c:30:14: note: each undeclared identifier is reported only once for each function it appears in
17899186/source.c:34:25: error: ‘next’ undeclared (first use in this function)
        new_node->next = next;
                         ^~~~
17899186/source.c:16:17: warning: variable ‘temp’ set but not used [-Wunused-but-set-variable]
    struct node* temp;
                 ^~~~
17899186/source.c: In function ‘print_list’:
17899186/source.c:45:5: error: unknown type name ‘Struct’; did you mean ‘struct’?
     Struct node *temp = head;
     ^~~~~~
     struct
17899186/source.c:45:17: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
     Struct node *temp = head;
                 ^
17899186/source.c:46:11: error: ‘temp’ undeclared (first use in this function); did you mean ‘bcmp’?
     while(temp != NULL)
           ^~~~
           bcmp

Answer 1

好吧，让我们仔细看看您得到的错误和警告:

warning: passing argument 1 of ‘strcmp’ makes pointer from integer without a cast [-Wint-conversion]warning: passing argument 2 of ‘strcmp’ makes pointer from integer without a cast [-Wint-conversion]这些警告说strcmp需要一个指针，但是您已经给它传递了一个整数。即使这是一个警告，而不是一个错误(这应该是IMO错误)，您仍然应该在继续操作之前进行修复。

note: expected ‘const char *’ but argument is of type ‘char’这显示了strcmp参数的预期类型和提供的类型。您传递了char变量((*head_ref)->data和new_node->data)，但是strcmp期望使用const char*，它是指向字符的指针(对于strcmp，基本上是字符串)

error: ‘current’ undeclared (first use in this function)error: ‘next’ undeclared (first use in this function)您尚未在此函数中声明current和next。

warning: variable ‘temp’ set but not used [-Wunused-but-set-variable] struct node* temp;变量temp被分配了一个值，但未使用。这基本上是报告未使用的变量，您可以忽略此警告

error: unknown type name ‘Struct’; did you mean ‘struct’?错误是不言自明的，甚至提供了解决方案。 C区分大小写。

error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ tokenerror: ‘temp’ undeclared (first use in this function); did you mean ‘bcmp’?由于前一个错误而引发了这些错误。修复拼写错误Struct-> struct时，这些应该会消失。

您应该注意 char data;可以包含单个字符，不能包含整个字符串。如果需要存储字符串，则必须使用 char data[64];这样的数组。 64表示数组的大小。这意味着 data最多可以存储63个字符(NUL终止符 \0的末尾为+1)。有多种方法可以使大小动态变化，但这是另一天的主题:-)