Clearing up minor warnings from compiler

[Dantin]

    Heres the compiler warnings:

arena.c: In function `do_startwar':
arena.c:55: warning: implicit declaration of function `atoi'
arena.c:90: warning: implicit declaration of function `do_wartalk'
arena.c: In function `do_war':
arena.c:142: warning: implicit declaration of function `do_look'


     Heres something probably so simple. I'm just overlooking it. In this
Arena.c I have a function do_wartalk and do_look. do_wartalk is initialized
like this:

do_wartalk(buf);
also do_look like this:
do_look(ch,"auto")

How can I make it to where the compiler doesn't whine about it.
Also I've been trying to get the atoi error to disappear.. The code looks
like this:

void do_startwar(CHAR_DATA *ch, char *argument)
{
  char buf[MAX_STRING_LENGTH];
  char arg1[MAX_INPUT_LENGTH], arg2[MAX_INPUT_LENGTH];
  char arg3[MAX_INPUT_LENGTH];
  DESCRIPTOR_DATA *d;

  argument = one_argument(argument, arg1);
  argument = one_argument(argument, arg2);
  argument = one_argument(argument, arg3);
  if (arg1[0] == '\0' || arg2[0] == '\0' || arg3[0] == '\0')
  {
    send_to_char("{BSyntax{W: {Bstartwar {Y<{Wtype{Y> <{Mmin_level{Y>
<{Mmax_level{Y>{x\n\r", ch);
    return;
  }

  if (atoi(arg1) < 1 || atoi(arg1) > 2)
  {
    send_to_char("{CThe type either has to be {W1{C, or {W2{C.{x\n\r", ch);
    return;
  }

  if (atoi(arg2) <= 0 || atoi(arg2) > 250)
  {
    send_to_char("{CLevel must be between {W1 {Cand {W250{C.{x\n\r", ch);
    return;
  }

  if (atoi(arg3) <= 0 || atoi(arg3) > 250)
  {
    send_to_char("{CLevel must be between {W1 {Cand {W250{C.{x\n\r", ch);
    return;
  }

  if (atoi(arg3) < atoi(arg2))
  {
    send_to_char("{CMax level must be greater than the min level.{x\n\r",
ch);
    return;
  }

      Any help is appretiated..

                                Dantin