#property indicator_chart_window
extern int 警戒均线=20;
int mark=0;
int start()
{
if( iHigh(0,0,0) >= iMA(0,0,警戒均线,0,MODE_SMA,PRICE_CLOSE,0)
   && iHigh(0,0,1) <   iMA(0,0,警戒均线,0,MODE_SMA,PRICE_CLOSE,1)
   && mark != 1 )
      {
         Alert(Symbol(),"向上触及20均线");
         mark = 1;
      }

if( iLow(0,0,0) <= iMA(0,0,警戒均线,0,MODE_SMA,PRICE_CLOSE,0)
   && iLow(0,0,1) >   iMA(0,0,警戒均线,0,MODE_SMA,PRICE_CLOSE,1)
   && mark != 2 )
      {
         Alert(Symbol(),"向下触及20均线",警戒均线,"均线");
         mark = 2;
      }
return(0);
}