NOOB Question!

We have a function like this:

Code:

void DS_append(DynString ds, char *newtxt)

And we need to ask the user for an integer input and then append it. So I have:

Code:

  int x;
  printf("Please enter a number: ");
  scanf("%d", &x);

  DS_append(ds, x); // This is line 29

But when I compile it gives me:

Code:

ex5.c:29: warning: passing argument 2 of ‘DS_append’ makes pointer from integer without a cast

And when I run it, of course, the much dreaded...

Code:

Segmentation fault

I've tried every combination of
DS_append(ds, &x);
DS_append(ds, (char) x);
DS_append(ds, (char *) x);
DS_append(ds, (char *) &x);

But none seem to work.

Can anyone figure out what I'm doing wrong here?

You need a string, you have an integer. You need to convert from one to the other (I would recommend sprintf to "print" the integer into a string).

Originally Posted by tabstop

You need a string, you have an integer. You need to convert from one to the other (I would recommend sprintf to "print" the integer into a string).

After some quick googling:

Code:

  int x;

  printf("Please enter a number: ");
  scanf("%d", &x);

  char result[100];
  sprintf( result, "%d", x );

  DS_append(ds, result);

Works great! THANK YOU!!!

Originally Posted by Paul22000

After some quick googling:

Code:

  int x;

  printf("Please enter a number: ");
  scanf("%d", &x);

  char result[100];
  sprintf( result, "%d", x );

  DS_append(ds, result);

Works great! THANK YOU!!!

What is the purpose of taking the user's input, which is already a string, converting it to an integer with scanf(), only to convert it directly back to a string again with sprintf()? Why not just scan the user's input using '%s' instead of '%d' ?

Originally Posted by brewbuck

What is the purpose of taking the user's input, which is already a string, converting it to an integer with scanf(), only to convert it directly back to a string again with sprintf()? Why not just scan the user's input using '%s' instead of '%d' ?

We have to do some stuff with the int that is inputted. I thought about just doing that too hehe, but yeah, there is a reason for it being an int in the first place