public onPlayerReceiveItem( playerid, itemName[ ], description[ ], amount )
{
      printf(" Player %i got a %s", playerid, itemName );
}

public onPlayerRemoveItem( playerid, itemName[ ], amount )
{
      printf(" Player %i lost %i of %s", playerid, amount, itemName );
}

public onPlayerInventorySaved( playerid, directory[ ] ) 
{
      printf( "Player %i's inventory was just saved to %s", playerid, directory );
}

public onPlayerInventoryLoaded( playerid, directory[ ] )
{
      printf( "Player %i's inventory was just loaded from %s", playerid, directory );
}

countInventoryItems( clientid ) - Counts the amount of inventory items a player has.
listInventoryItems( clientid, inv_name[ ], inv_description[ ], &inv_int, &index ) - Lists all inventory items, view forum topic for information.
saveInventory( clientid, directory[ ] = INVENTORY_DIRECTORY ) - Saves a inventory.
loadInventory( clientid, directory[ ] = INVENTORY_DIRECTORY ) - Laods a inventory.
getInventoryItemDesc( clientid, itemName[ ] ) - Gets a item's description.
checkInventoryItemQuanity( clientid, itemName[ ] ) - Checks the amount of a item a player has.
checkInventoryItem( clientid, itemName[ ] ) - Checks if a player has a inventory item.
addInventoryItem( clientid, itemName[ ], description[ ], amount ) - Adds a inventory item.
removeInventoryItem( clientid, itemName[ ], amount = 0 ) - Removes a inventory item.
resetInventory( clientid ) - Resets a player's inventory.
        
onPlayerReceiveItem( playerid, itemName[ ], description[ ], amount ) - Called when a player gets item.
onPlayerRemoveItem( playerid, itemName[ ], amount ) - Called when a player loses a item.
onPlayerInventorySaved( playerid, directory[ ] ) - Called when a inventory is saved.
onPlayerInventoryLoaded( playerid, directory[ ] ) - Called when a inventory is loaded.

new
    bool:p_logged[ MAX_PLAYERS ]
;

public OnPlayerConnect( playerid )
{
     addInventoryItem( playerid, "cow", "this animal echos moo.", 2 ); // The player has two cows!
     addInventoryItem( playerid, "Pencil", "You can write with this object", 1 ); // The player has one pencil.
}

public OnPlayerDisconnect( playerid, reason )
{
     if( p_logged[ playerid ] == true )
         saveInventory( playerid );

     return true;
}

public OnPlayerCommandText( playerid, cmdtext[ ] )
{ 
     if( !strcmp( cmdtext, "/login", true ) )
     {
          ...
          OnPlayerLogin( playerid, password );
     }
     if( !strcmp( cmdtext, "/moo", true ) )
     {
           if( !checkInventoryItem( playerid, "cow" ) )
              return SendClientMessage( playerid, 0x0, "{FFFFFF}Since you don't have a cow, you cannot use this command" );
 
           ...
     }
     if( !strcmp( cmdtext, "/myinventory", true ) )
     {
          new 
              string[ 150 ],
              itemName[ 30 ],
              itemDesc[ 100 ],
              itemAmm
              idx
          ;
          SendClientMessage( playerid, 0x0, "{FFFFFF}You have the following items in your inventory:" );
          while( listInventoryItems( playerid, itemName, itemDesc, itemAmm, idx ) )
          {
               format( string, sizeof string, "{FFFFFF}%s - %s (Amount: %i)", itemName, itemDesc, itemAmm );
               SendClientMessage( playerid, 0x0, string );
               idx ++;
          }
          /*
              From the items given in OnPlayerConnect, this would print:
              cow - this animal echos moo (Amount: 2)
              Pencil - You can write with this object (Amount: 1)
          */
     }
}

public onPlayerReceiveItem( playerid, itemName[ ], description[ ], amount )
{
     if( !strcmp( itemName, "cow", true ) )
        return printf("Player %i is now cow-friendly", playerid );
}

public OnPlayerLogin( playerid, password )
{
     loadInventory( playerid );
     p_logged[ playerid ] = true;
}

Cyanide - Project Launcher & Developer
SA-MP Team - San Andreas Multiplayer Modification.

if(newkeys & KEY_YES)
    {
        new 
            itemName[30],
            itemDescription[100],
            itemAmount,
            index;
        strdel(DialogString, 0, sizeof(DialogString));
        strcat(DialogString, COLOR_HEX_RED"Item\t\t\t\t\tAnzahl\n");
        while(listInventoryItems(playerid, itemName, itemDescription, itemAmount, index))
        {
            format(DialogString, sizeof(DialogString), COLOR_HEX_WHITE"%s%s\t\t\t%d\n", DialogString, itemName, itemAmount);
            index++;
        }
        ShowPlayerDialog(playerid, DIALOG_INVENTORY, DIALOG_STYLE_LIST, "Inventar", DialogString, "Auswдhlen", "Abbrechen");
    }

case DIALOG_INVENTORY:
{
    if(response)
    {
        
    }
}

COMMAND:i(playerid, params[])
{
	new ilist[780];
 	new
   	itemName[ 30 ],
   	itemDesc[ 100 ],
   	itemAmm,
   	idx;
   
   while( listInventoryItems( playerid, itemName, itemDesc, itemAmm, idx ) )
   {
   		format( ilist, sizeof ilist, "{FFFFFF}%s - %s (Amount: %i)\n%s", itemName, itemDesc, itemAmm , ilist);
      	idx ++;
   }
    ShowPlayerDialog(playerid, 789, DIALOG_STYLE_LIST, "Inventory", ilist, "Close", "Close");
    return 1;
}