Code example: How to know when BUY/SELL signal changes?

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Hi, I have a question.

Receiving buffer signal from the indicator, I want to make BUY/SELL order

when trend color changes.

Attached indicator shows buffer signal such as

Buffer1 =BUY

BUffer2 =SELL

I can order if buffer1 or buffer2 is not EMPTY_VALUE.

However,if I do this, so many BUY/SELL orders are made....

How can I know when the signal changes from blue to white/ white to blue?

I just want to place order when color changes..

Appreciate if you give some ideas or an example code.

Thanks a lot!

         int ret=0;
         int limit=1;
for(int k=1;k<=limit;k++){
         double buy=iCustom(NULL,TimeScale,indicator_name,k);
         double sell=iCustom(NULL,TimeScale,indicator_name,k);
         if (buy!=EMPTY_VALUE) 
         {
                 ret=1;
                 Print("BUY signal"+buy);
                 
         }
         else if(sell!=EMPTY_VALUE) 
         {
                 ret=-1;
                 Print("SELL signal"+sell);
         }
         return(ret);
}
}
Files:
VarMA_indicator.mq4  9 kb
 
Usually if the bar you are checking !=EMPTY_VALUE and the previous bar value  ==EMPTY_VALUE, then it has just changed.
 
Keith Watford:
Usually if the bar you are checking !=EMPTY_VALUE and the previous bar value  ==EMPTY_VALUE, then it has just changed.

Hi, Keith, Thank you for your comment.

Wow,what a simple one.. I did not know it.

In this case, 

 int ret=0;
         int limit=1;
for(int k=1;k<=limit;k++){
         double buy=iCustom(NULL,TimeScale,indicator_name,k);
         double sell=iCustom(NULL,TimeScale,indicator_name,k);

I can compare with !=EMPTY_VALUE (k) and ==EMPTY_VALUE (k-1) previous one, right?

  
 int ret=0;
         int limit=1;
for(int k=1;k<=limit;k++){
         double buy=iCustom(NULL,TimeScale,indicator_name,k);
         double sell=iCustom(NULL,TimeScale,indicator_name,k);

I don't know what the point of the loop is as it will only loop once.

Your doubles buy and sell are both given the same value - why?

  
 int ret= 0 ;
 //int limit=1; 
 //for(int k=1;k<=limit;k++){ 
   double buy=iCustom(NULL,TimeScale,indicator_name,1,1);   //double buy=iCustom(NULL,TimeScale,indicator_name,k); 
   double sell=iCustom(NULL,TimeScale,indicator_name,2,1);  //double sell=iCustom(NULL,TimeScale,indicator_name,k);

Buffer numbers are not specified.

Since k is always 1, there is no need to loop it. 

 

Oh, that is my mistake.... Need buffer#.

Now I see, the loop is only once, so I don't need to loop it.

I will try again. Thank you so much.

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