[Macluawn]

with your example the pin could be 3digit, 2digit and even 1digit number.
use

Код:

pin =  1000+random(8999);

with this the pin minimum can be 1000 and maximum of 9999 (1000+8999=9999)

My version of your code -

Код:

stock GenerateBankPin(playerid) 
{
  new pin =  1000+random(8999); //generates a number
  for ( new i = 0; i < GetMaxPlayers() ; i++ )  //loops through all the server player slots (defined in server.cfg)
  {
    if ( IsPlayerConnected ( i ) && pBankPin [ i ] ==  bpin && i!=playerid) pin =  1000+random(8999); //checks if player in that slot is connected and if its pin is the same as the playerid's then it generates a new pin.
  }
  return pin;
}

This isn't the best sollution offcourse and in some cases the number may be the same.