structure pointer problem in c when reading string using structure pointer

Question

5.00/5 (1 vote)

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C++

struct book
{
	char name[50];
	char author[50];
	int page;
	float price;
};
int main()
  {
  	 struct book *x;
  	 printf("name : ");
  	 gets(x->name);
  	 printf("author : ");
  	 gets(x->author);
  	 printf("page : ");
  	 scanf("%d",&x->page);
  	 printf("price : ");
  	 scanf("%f",&x->price);
  	 printf("\n%s\t%s\t%d\t%f",x->name,x->author,x->page,x->price);
  	 getch();
  	 return 0;
  }

this code is not working properly and giving a segmentation fault

Posted 23-May-14 21:04pm

Vivek_Maruxxxx

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2 solutions

Solution 2

You didn't initialize the structure pointer x. I guess you're using C++ by seeing your question's tags. Do it in this way.

C++

struct book *x;
x = new book;
printf("name : ");
.....

Posted 23-May-14 23:26pm

Manikandan10

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Richard MacCutchan · Accepted Answer · 2014-05-23T21:51:00

I'm not surprised it gives a segmentation fault. In main you have;

C++

  	 struct book *x;
  	 printf("name : ");
  	 gets(x->name);
...

So you have created the pointer x but it does not point to anything, hence the seg fault. You need to initialise it so that it points to an actual memory structure. This is done by a call to malloc thus:

C++

struct book *x;
    // allocate a new book structure on the heap
    x = (struct book *)malloc(sizeof(struct book));
printf("name : ");
gets(x->name);