Thread: Using a pointer to a string to insert characters (spaces) and shift the remainder?

If I have a string, char str
and a pointer to a string char *ptr
and using curses.h with direct terminal input/output #DEFINE TAB_KEY 9 ASCII
and the cursor position on the string int *curpos

How can I do the following,

Code:

ABCDEF<--cursor here & hit tab (defined 4 spaces-->GHIJKL

or

Code:

<--cursor here & hit tab (4 spaces inserted)-->ABCDEFGHIJKL

I know that I am going to be using a for loop, I just am struggling with with the conditions.

Appreciate any help as always.

Well, if you have a string, and you want to insert 4 spaces into it, you'd do it something like:

Code:

{
  char *p;

  // Move everything after curpos 4 spaces to the right
  for(p = curpos + strlen(curpos) ; p >= curpos ; p--);
    *(p + 4) = *p;

  // Insert 4 spaces starting at curpos
  for(p = curpos ; p - curpos < 4 ; p++)
    *p = ' ';
}

Like TactX said, you could also do it with a memmove() and a memset() function call. Assuming the same stuff as in my last post:

Code:

memmove(curpos + 4, curpos, strlen(curpos) + 1);
memset(curpos, ' ', 4);

How can I do strlen(curpos), if is not of type string?

To be honest, I can't tell what the hell curpos is. From the name I figured you probably either a) Typo'd the type as int instead of char, or b) accidentally typo'd it as a pointer instead of a plain int like an index usually is.

Is it a pointer to an index into the string then? If so, use strlen(str + *curpos) instead of strlen(curpos).

You didn't explain what it was very well, and why it's a pointer is still a mystery to me. Anyway, you have the concept of what you need to do so you should be able to do it now. Move everything from curpos to the end 4 spaces to the right, then stick 4 spaces in starting at curpos.