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
而且我无法弄清楚为什么我收到此错误消息已经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;
并且 first 和 mark 是这样定义的变量
struct node *first;
int mark = 0;
对此的任何帮助将不胜感激我花了几个小时试图调试这个错误。编写 C 代码是我目前生活的祸根。
Ps 我已经检查了 llistlib.c 文件和 llistdriver.c 文件中包含的所有#include "llistlib.h"。
好吧，也许这会让它更清楚
// llistlib.c - 实现 listlib.h 文件中定义的函数的库 #include #include #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 读取为
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);
我还没有在任何代码中发现明显的问题