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:

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

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or

Code:

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

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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.

I may get you wrong, but I think memmove() would please you.

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

Code:

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{
  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 = ' ';
}

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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:

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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.

Oops that's a mistake I made in the begining, here, I'll try my best to exaplain. The pointer "curpos" points to an integer holding the position of the cursor in the field (0 is the first position).

One thing: char str is not a string, it's a single character, so I hope you aren't using it as a string...

nope