MT4 Coding Question: Buffers and Arrays

[Arthur Ockwell]

Hello folks,

I am attempting to code an Custom Indicator but to arrive and the final value for putting into the IndexBuffers I need very much more than 8 indicator_buffers.

I have created a set of Arrays and in the Init code:

   ArrayResize(bufferVolgv, Bars);
   ArraySetAsSeries(bufferVolgv, true);

My question is this.

When a new bar is created, the IndexBuffers must add 1 to the array size so that there is a node for the new data to be written to. As "bufferVolgv" has not been assigned to an IndexBuffer, do I need to trap an event when a new bar is created, and manually execute an ArrayResize? My thinking is that if I don't add a new node, the data for the new bar (bufferVolgv[0]) will overwrite the data for the previous bar.

When an array is assigned to an IndexBuffer, MT4 must handle this automatically.

Or am I over thinking all this?

Thanks

Art

[Simon Gniadkowski]

HiArt99:

Hello folks,

I am attempting to code an Custom Indicator but to arrive and the final value for putting into the IndexBuffers I need very much more than 8 indicator_buffers.

I have created a set of Arrays and in the Init code:

My question is this.

When a new bar is created, the IndexBuffers must add 1 to the array size so that there is a node for the new data to be written to. As "bufferVolgv" has not been assigned to an IndexBuffer, do I need to trap an event when a new bar is created, and manually execute an ArrayResize? My thinking is that if I don't add a new node, the data for the new bar (bufferVolgv[0]) will overwrite the data for the previous bar.

Read this thread: https://www.mql5.com/en/forum/147625 and check that you are resizing your Series arrayss correctly

[Arthur Ockwell]

Thought so but was worth checking. Thanks you Raptor.

[William Roeder]

   ArrayResize(bufferVolgv, Bars);
   ArraySetAsSeries(bufferVolgv, true);

Will not work because you are not moving elements left as you add more bars. Use this (from my polyline code):

bool     ResizeBuffer(double& buffer[], int size){ // buffer can be 1D or 2D
   if(ArrayRange(buffer,0) != size){      // ArrayRange allows 1D or 2D arrays
      ArraySetAsSeries(buffer, false);    // Shift values B[2]=B[1]; B[1]=B[0]
      if( !MyArrayResize(buffer, size, "ResizeBuffer") )        return(false);
      ArraySetAsSeries(buffer, true);
   }
   return(true);
}
bool     MyArrayResize(double& arr[], int nRows, string msg){
   if( ArrayResize(arr, nRows) >= nRows)  return(true);
   DisableTrading( "ArrayResize("+nRows+") Failed: "+GetLastError() +" "+msg);
   return(false);
}

and remember that new elements have not been set to EMPTY_VALUE

[Arthur Ockwell]

Thanks