MQL4 check please for closing half trade

Will this EA monitor open trades for the chart and close half the trade on reaching a certain target profit and move the stop loss to plus 10 pips of the opening price?

Have I missed anything in the code?

How could I stop it acting on the half closed order the next time the tick runs?

//+------------------------------------------------------------------+
//| Close half trade and move SL to +10.mq4 |
//| Copyright © 2009, MetaQuotes Software Corp. |
//| http://www.metaquotes.net |
//+------------------------------------------------------------------+
#property copyright "Copyright © 2009, MetaQuotes Software Corp."
#property link "http://www.metaquotes.net"
#property show_inputs

extern double SL = 100; //move to plus 10 pips / generally use the ATR value from the chart
extern double TP = 500; //50pips or otherwise specified or ATR value from the chart

//+------------------------------------------------------------------+
//| expert initialization function |
//+------------------------------------------------------------------+
int init()
{
//----

//----
return(0);
}
//+------------------------------------------------------------------+
//| expert deinitialization function |
//+------------------------------------------------------------------+
int deinit()
{
//----

//----
return(0);
}
//+------------------------------------------------------------------+
//| expert start function |
//+------------------------------------------------------------------+
int start()
{

//+------------------------------------------------------------------+
//| Find open positions |
//+------------------------------------------------------------------+

//----

double halfLot;

for(int i=0;i<OrdersTotal();i++)
{
if(OrderSelect(i,SELECT_BY_POS,MODE_TRADES)==false) break;

if(OrderSymbol()==Symbol())
{
if(OrderType()==OP_BUY && Ask-OrderOpenPrice() >= TP) {
halfLot = MathRound(OrderLots()/2,2);
OrderClose(OrderTicket(),halfLot,Ask,NULL,Green);
OrderModify(OrderTicket(),OrderOpenPrice(),OrderOpenPrice()+SL,OrderTakeProfit(),0,Green);
}
if(OrderType()==OP_SELL && OrderOpenPrice()-Bid >= TP) {
halfLot = MathRound(OrderLots()/2,2);
OrderClose(OrderTicket(),halfLot,Ask,NULL,Red);
OrderModify(OrderTicket(),OrderOpenPrice(),OrderOpenPrice()+SL,OrderTakeProfit(),0,Red);
}
}
}

//----
//+------------------------------------------------------------------+

}