usage of strcpy in functions

Question

#include<stdio.h>
#include<stdlib.h>
#include<ctype.h>
#include<string.h>

struct person *create_node(char *, char *,int);
void addnode(char *,char *,int,struct person *);


struct person
{
   char fname[20];
   char sname[20];
   int pno;
   struct person *next,*prev;
};

struct person *create_node(char *first,char *second,int mob)
{
   struct person *pnode=(struct person *)malloc(sizeof(struct person));
   strcpy(pnode->fname,*first);
   strcpy(pnode->sname,*second);
   pnode->pno=mob;
   pnode->next=pnode->prev=NULL;

  return pnode;

 }

 void addnode(char *first,char *second,int mob,struct person *pnode)
 {
   while(pnode->next!=NULL)
   {
        pnode=pnode->next;
   }
   pnode->next=create_node(first,second,mob);
   pnode->next->prev=pnode;

 }

 int main()
 {
   struct person *root=NULL;
   char choice='y';
   char first[20];
   char second[20];
   int mob;

   while(tolower(choice)=='y')
  {
        printf("enter the first name:");
    scanf("%s",first);

    printf("enter the second name:");
    scanf("%s",second);

    printf("enter the mobile no:");
    scanf("%d",&mob);

    if(root==NULL)
    root=create_node(first,second,mob);
    else
    addnode(first,second,mob,root);
    printf("enter the option to continue or end(y or n):");
    scanf("%c",&choice);
    fflush(stdin);
  }

  return 0;
  }

This is the program I have written,what it basically does is,it will create linked list taking the values of the structures from the users.

I got 2 similar warnings when i run this program from the function

    struct person * create_node(char *, char *, int),
    passing char to argument 2 of strcpy(char *, const char *) lacks a cast

I don't understand why it is passing const value to the function.

And I have one more problem with this program.The program stops working after I enter the information for first node.

I am using gcc compiler on windows platform. Please help me out. Thanks...

Your code doesn't do any length checking. If anyone enters more than 19 characters in their name, bad things will happen. — DCoder, Sep 23 '12 at 05:29

score 4 · Accepted Answer · edited May 23 '17 at 10:25

4

The problem is not that. The problem is that you're passing *first and *second as the second argument for strcpy() which are chars and not char pointers. You must simply pass first and second, the pointers themselves.

Also, please do not cast the return value of malloc.

edited May 23 '17 at 10:25

Community

1
1

answered Sep 23 '12 at 05:27

@user1632141 Precisely, which is the warning? – Sep 23 '12 at 05:47
ANSI C++ forbids implicit conversion from `void *' in initialization – starkk92 Sep 23 '12 at 05:49
1

You tagged this question `c`, not `c++`. If it's actually a `C++` program, you're going to get wrong advice. – David Schwartz Sep 23 '12 at 05:52
@user1632141 Wow... That's not my fault! You tagged this question as C, this code seems to be C, ... yet you compile/treat it as C++. Don't do that. – Sep 23 '12 at 05:53

score 2 · Answer 2 · answered Sep 23 '12 at 05:30

Here:

struct person *create_node(char *first,char *second,int mob)
{
   // ...
   strcpy(pnode->fname,*first);
   strcpy(pnode->sname,*second);
   // ...
   return pnode;
}

first and second are pointers (to char). There's no reason to dereference them with * and extract the chars. strcpy() takes pointers as its arguments. first and second are good for strcpy() as they are.

usage of strcpy in functions

2 Answers2