need help.. If item is equip in source code

[Jaycee KyD]

hi there anyone can help me in this source code. sample i want to make extra damage if the player equip the item( id code ) in source code not in item_db. 

EXAMPLE:

DARKNESSATTACK:
        if (sd->equip_index[EQP_HEAD_TOP] == 19001 ) { skillratio += 500 + 40 * skill_lv;
 break; }
            skillratio += 300 + 40 * skill_lv;
            break;

this code is not working  if (sd->equip_index[EQP_HEAD_TOP] == 19001 ) is there anyone can help me? thank you in advance

[Magnetix]

if (sd->equip_index[EQI_HEAD_TOP] >= 0 && sd->inventory_data[sd->equip_index[EQI_HEAD_TOP]]->nameid == 19001)
	skillratio += 500 + 40 * skill_lv;
else
	skillratio += 300 + 40 * skill_lv;
break;

Make sure to recompile.