我收到这样的错误:
$ gcc -o app llistdriver.c llistlib.c -Wall
llistdriver.c:7: warning: return type defaults to `int'
llistdriver.c: In function `printinsts':
llistdriver.c:15: warning: control reaches end of non-void function
llistlib.c: In function `insert':
llistlib.c:25: warning: statement with no effect
llistlib.c:41: warning: control reaches end of non-void function
/tmp/ccqYmK3M.o:llistdriver.c:(.text+0x157): undefined reference to `_search'
collect2: ld returned 1 exit status
而且我不知道为什么我收到此错误消息，并编写了一个包含链接列表方法的库文件。
int search( struct node *front, int val)//
{
while(front != NULL)
{
if( front->modmark == val ) //this is to find the value
return 1; // found it
front=front->next;
}
return 0; // Not found
}
我认为它正在抱怨主文件中的唯一引用
case 5:
printf("please enter a search value?\n");
scanf("%i",&mark);
choice = search(first,mark);//here
if (choice == -1)
{
printf("the modmark was not found\n");
}
else
{
printf("the first occurence of the mark is at the %i th index of the list",choice);
};
break;
和first和mark是这样定义的变量
struct node *first;
int mark = 0;
在此方面提供的任何帮助将不胜感激，因为我花了数小时尝试调试此错误。目前，编写C代码是我一生的 Backbone 。
附言:我已经检查了所有的#include“lliSTLib.h”，它们都包含在lliSTLib.c文件和llistdriver.c文件中。
好吧，这可能会使它更清晰
//lliSTLib.c-实现liSTLib.h文件中定义的功能的库
＃包括
＃包括
#include“lliSTLib.h”
void initialise(struct node **ps)
{
printf("initialise function\n");
*ps = NULL; //initialise list to empty
}
int insert(struct node **fn)
{
printf("insert function\n");
struct node *newnode;
newnode = (struct node*) malloc(sizeof (struct node)); //make new node and give it memory
if (newnode == NULL) //if fsiled return to the program saying it failed
return -1;
if (*fn == NULL) // for the first of the list
{
newnode -> next == NULL; // sets the next value to nothing
printf("what mark do you want to enter\n");
scanf("%i",&newnode -> modmark); // this gets the modmark
*fn = newnode; //the head of the list is set to the new node
}
else
{
newnode -> next = *fn; // sets the newnodes next value to the head node
printf("what mark do you want to enter\n");
scanf("%i",&newnode -> modmark); // gets the modmark
*fn = newnode; // the head becomes the new node
printf("%p %i",newnode,newnode->modmark); // just for debugging
}
}
void traverse(struct node *ps)
{
if (ps != NULL) // if the current node is null
{
printf("%p - %i\n",ps,ps -> modmark);
traverse(ps -> next);
}
else
{
printf("your list is empty\n");
}
}
void delete(struct node **dn)
{
printf("delete function\n");
struct node *delnode;
delnode = *dn; //sets the head node so that it can be deleted later
if (delnode != NULL)
{
*dn = delnode -> next; // sets the head to the next node
free(delnode); //deletes the previous head node
}
}
void finish(struct node **ps) //this function goes through the list and removes all items
{
printf("finish function\n");
struct node *finishnode;
finishnode = *ps;
while (finishnode != NULL)
{
*ps = finishnode -> next;
free(finishnode);
finishnode = *ps;
}
int search(struct node *front,int val)
{
while(front != NULL)
{
if( front->modmark == val ) // Assuming struct node has val member which you are trying to compare to
return 1; // found it
front=front->next;
}
return 0; // Not found
}
}
然后llistdriver.c文件是
#include <stdio.h>
#include <stdlib.h>
#include "llistlib.h"
printinsts()
{
printf("Enter:- \n");
printf("\t0 to exit\n");
printf("\t1 to initialise list\n");
printf("\t2 to insert item at front of list\n");
printf("\t3 to delete item from front of list\n");
printf("\t4 to traverse list\n");
printf("\t5 to search through the list\n");
}
int main()
{
int choice;
struct node *first;
int mark = 0;
printinsts();
scanf("%d",&choice);
while (1)
{
switch (choice)
{
case 0 : finish(&first);
exit(0);
break;
case 1 : initialise(&first);
break;
case 2 : if (insert(&first)== -1)
{
printf("insert not successful");
choice = 0;
};
break;
case 3 : delete(&first);
break;
case 4 : traverse(first);
break;
case 5:
printf("please enter a search value?\n");
scanf("%i",&mark);
choice = search(first,mark);
if (choice == -1)
{
printf("the modmark was not found\n");
}
else
{
printf("the first occurence of the mark is at the %i th index of the list",choice);
};
break;
default : printf("Invalid choice of %d \n", choice);
}; // end of switch
printinsts();
scanf("%d", &choice);
} // end of while
}
头文件lliSTLib.h读为
struct node {
int modmark;
struct node *next;
};
void initialise(struct node **ps);
int insert(struct node **fn);
void traverse(struct node *ps);
void delete(struct node **dn);
void finish(struct node **ps);
int search(struct node *front,int val);
我还没有发现任何代码中的明显问题
最佳答案
您的finish函数缺少右括号{。 search有一个额外的大括号。
关于c - 为什么我在执行单链列表时在C中收到 undefined reference 错误，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/13984765/