[英]Incompatible types struct* and struct,
感谢您花时间阅读我的问题,我查看了一些类似的问题,它们在这种情况下似乎没有帮助,尽管可能会帮助其他遇到类似问题的人:
C:不兼容的类型?
结构为 C 中不兼容的指针类型
结构 C 的不兼容类型错误
我正在尝试在 c (-std=c99) 中创建一个简单的链表结构,此时我的结构相当通用:
typedef struct
{
int count;
char* word;
struct node *nextNode;
}node;
然后在一个函数中,我有一个“根”或“头”节点:
node *root;
root = (node *) malloc(sizeof(node));
我尝试稍后在函数中将节点分配给node
nextNode
,如下所示:
if(root->nextNode == 0)
{
root->nextNode = foo;
}
这导致错误:
“从类型node
分配到类型struct node*
时,错误不兼容类型
&foo
不会改善这种情况,而是导致lvalue required as unary
样式错误。
这是围绕我的问题的上下文:
#include <stdio.h>
#include <malloc.h>
#include <string.h>
typedef struct
{
int count;
char* word;
struct node *nextNode;
}node;
node makenode(char *word)
{
node x;
x.word = word;
x.count = 1;
return x;
}
void processInput(int threshold, const char* filename)
{
node *root;
root = (node *) malloc(sizeof(node));
root->nextNode = 0;
char* word;
while(fgets(word, 29, stdin) != NULL){
if(root->nextNode == 0)
{
root->nextNode = makenode(word);
}
问题
typedef struct // make an alias for a structure with no tag name
{
int count;
char* word;
struct node *nextNode; // with a pointer to struct node (which does not exit)
}node; // name the alias node
解决方案
typedef struct node // make an alias for a structure with tag name node
{
int count;
char* word;
struct node *nextNode; // with a pointer to struct node (which is this one)
}node; // name the alias node
试试这个代码
#include <stdio.h>
#include <malloc.h>
#include <string.h>
typedef struct node //should give a name for this
{
int count;
char* word;
struct node *nextNode;
}node;
static node *makenode(char *word) //start with static and returning type is node* because we are storing this output in root->nextNode which is *node pointer
{
node x;
x.word = word;
x.count = 1;
return x;
}
void processInput(int threshold, const char* filename)
{
node *root;
root = (node *) malloc(sizeof(node));
root->nextNode = NULL; //pointer values should initialised to NULL not 0
char* word;
while(fgets(word, 29, stdin) != NULL){
if(root->nextNode == NULL) ////pointer values should initialised to NULL not 0
{
root->nextNode = makenode(word);
}
}
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