C 中的链表

Question

当我编译这个程序时，我在第 45 行（已注释）中收到一个错误，指出 strcpy 的隐式声明不兼容...我复制了该代码的一部分，希望你们可以帮助我

#include <stdio.h>

#include <stdlib.h>

#define strsize 30

typedef struct member
{int number;
char fname[strsize];
struct member *next;
}
RECORD;

RECORD* insert (RECORD *it);
RECORD* print(RECORD *it, int j);

int main (void)
{
int i, result;
RECORD *head, *p;
head=NULL;
printf("Enter the number of characters: ");
scanf("%d", &result);

for (i=1; i<=result; i++)
head=insert (head);
print (head, result);

return 0;

}

RECORD* insert (RECORD *it)

{

RECORD *cur, *q;
int num;
char junk;
char first[strsize];
printf("Enter a character:");
scanf("%c", &first);

cur=(RECORD *) malloc(sizeof(RECORD));

strcpy(cur->fname, first);
cur->next=NULL;

if (it==NULL)
it=cur;

else
{
q=it;
while (q->next!=NULL)
q=q->next;
q->next=cur;
}
return (it);
}
RECORD* print(RECORD *it, int j)
{
RECORD *cur;
cur=it;
int i;
for(i=1;i<=j;i++)
{
printf("%c \n", cur->fname);
cur=cur->next;
}
return;
}

使用 GCC 来解决这个问题

Answer 1

您可能需要添加

#include <string.h>

以获取 strcpy() 的声明。

Answer 2

不是因为这比安德鲁的答案更好，而是因为 gcc 给我的关于您的代码的所有警告都不太适合注释。

/usr/bin/gcc    -c -o str.o str.c
str.c: In function 'insert':
str.c:53: warning: format '%c' expects type 'char *', but argument 2 has type 'char (*)[30]'
str.c:57: warning: incompatible implicit declaration of built-in function 'strcpy'
str.c: In function 'print':
str.c:79: warning: format '%c' expects type 'int', but argument 2 has type 'char *'

gcc 一定给了你“隐式声明”的警告，不要忽视这样的事情。更好的是，使用 c99 和选项 -Wall 来获取更多警告，然后将其全部纠正。

c99 -Wall   -c -o str.o str.c
str.c: In function 'main':
str.c:30: warning: unused variable 'p'
str.c: In function 'insert':
str.c:52: warning: format '%c' expects type 'char *', but argument 2 has type 'char (*)[30]'
str.c:56: warning: implicit declaration of function 'strcpy'
str.c:56: warning: incompatible implicit declaration of built-in function 'strcpy'
str.c:49: warning: unused variable 'junk'
str.c:48: warning: unused variable 'num'
str.c: In function 'print':
str.c:78: warning: format '%c' expects type 'int', but argument 2 has type 'char *'
str.c:81: warning: 'return' with no value, in function returning non-void