program quit automatically

**guest18** · 08-06-2009

Code:

#include <stdio.h>

typedef struct {
   char* author;
   char* title;
   char* isbn;
   int edition;
} Book;

int main()
{
   int howmanyrecords;
   int counter=0;
       
   printf("How Many Record you want ?");
   scanf("%d",&howmanyrecords);
   
      Book *pbook[howmanyrecords];
   
 
         for(counter=0;counter<=howmanyrecords;counter++) 
   {
         pbook[counter] = (Book*)malloc(sizeof(Book));
                   
         printf("counter number is %d \n",counter);
         
         printf("enter author\n");
         scanf("%s",pbook[counter]->author);
   
         printf("enter title\n");
          scanf("%s",pbook[counter]->title);
         
         printf("enter isbn\n");
          scanf("%s",pbook[counter]->isbn);
         
         printf("enter edition\n");
         scanf("%d",pbook[counter]->edition);
        
        
        } 
        
        
   for (counter=0;counter <= 0;counter++)
   {
              
        printf ("record %d author is %s and the title is %s and the isbn %s is and the edition is%d\n"
               ,counter,pbook[counter]->author,pbook[counter]->title,pbook[counter]->isbn,pbook[counter]->edition);
         
        
        }   
         

   
   return 0;
   }

the program quit automatically after entering isbn. any idea ?

**Spidey** · 08-06-2009

Cprogramming.com FAQ > How do I get my program to wait for a keypress?

**bithub** · 08-06-2009

You are trying to write strings to pointers. Try defining your books like:

Code:

typedef struct {
   char author[100];
   char title[100];
   char isbn[100];
   int edition;
} Book;

Now each of those variables can hold 99 characters plus a null terminator character. The other problem is when you read in the edition. You need to pass a variable pointer to scanf, not the variable's value. Also, you are reading in 1 more record than the user told you to. Look at your for loop declaration for the reason why.

**guest18** · 08-06-2009

Originally Posted by Spidey

Cprogramming.com FAQ > How do I get my program to wait for a keypress?

uhh the program arent suppose to quit at that stage, it still have another line to execute to enter

Originally Posted by bithub

You are trying to write strings to pointers. Try defining your books like:

Code:

typedef struct {
   char author[100];
   char title[100];
   char isbn[100];
   int edition;
} Book;

Now each of those variables can hold 99 characters plus a null terminator character. The other problem is when you read in the edition. You need to pass a variable pointer to scanf, not the variable's value. Also, you are reading in 1 more record than the user told you to. Look at your for loop declaration for the reason why.

well Book *pbook[howmanyrecords]; <- this already declare the pbook as pointer, if I put scanf with &, it wont work

well using author[100] and author* produce same result.

about the forloop issue, I Will look onto it but for now I really need to know why it stop executing the rest of the program after entering isbn

ohh nvm the reason why it quit is I havent allocate memory for the pointer variable inside the struct, that why array of 100 work as well but didnt quit

**bvkim** · 08-06-2009

Code:

#include <stdio.h>

typedef struct _Book {
   char* author; /* better set statically like char author[30] */
   char* title; /* better set statically */
   char* isbn; /* better set statically */
   int edition;
} Book;

int main()
{
   int howmanyrecords;
   int counter=0;
       
   printf("How Many Record you want ?");
   scanf("%d",&howmanyrecords);
   
      Book *pbook[howmanyrecords];
   
 
         for(counter=0;counter< howmanyrecords;counter++)  /* max record: count from 0 to MAX - 1 */
   {
         pbook[counter] = (Book*)malloc(sizeof(Book));
                   
         printf("counter number is %d \n",counter + 1); /* counter = index + 1 */
         
         printf("enter author\n");
	/* if dynamically, then allocate memory first */
         scanf("%s",pbook[counter]->author);
	/* if dynamically, then allocate memory first */   
         printf("enter title\n");
          scanf("%s",pbook[counter]->title);
	/* if dynamically, then allocate memory first */         
         printf("enter isbn\n");
          scanf("%s",pbook[counter]->isbn);
       	/* if dynamically, then allocate memory first */
         printf("enter edition\n");
         scanf("%d",pbook[counter]->edition);
        
        
        } 
        
        
   for (counter=0;counter < howmanyrecords;counter++) /* not 0 */
   {
              
        printf ("record %d author is %s and the title is %s and the isbn %s is and the edition is%d\n"
               ,counter,pbook[counter]->author,pbook[counter]->title,pbook[counter]->isbn,pbook[counter]->edition);
         
        
        }   
         

   
return 0;
}

**guest18** · 08-06-2009

well the reason why it is pointer in the struct is because the question Im doing required me to do so

yeah, thanks alot, I shall go find way of allocating the pointer inside the struct

**GL.Sam** · 08-06-2009

>yeah, thanks alot, I shall go find way of allocating the pointer inside the struct

*facepalm*

dynamic array in STRUCT

**bvkim** · 08-07-2009

Originally Posted by guest18

well the reason why it is pointer in the struct is because the question Im doing required me to do so

yeah, thanks alot, I shall go find way of allocating the pointer inside the struct

malloc(), calloc()

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