function with array as return value?

New comment
 

is it possible to give an array as a return value, like this?


double[] function23(...)
{
   double erg[3];
   ...
   
   return (erg);
}
 
mql4_rulez:

is it possible to give an array as a return value, like this?



mql4_rulez,

You normally do this by returning a pointer to the array. Since pointers are not supported in mql4 seems impossible to do it that way.

Regards!

 
mql4_rulez wrote >>

is it possible to give an array as a return value, like this?

void function(double& erg[])

 
mql4_rulez wrote >>

is it possible to give an array as a return value, like this?

Like this:

//+------------------------------------------------------------------+
//| script program start function                                    |
//+------------------------------------------------------------------+
int start(){
   double array[10];
  
   myFunction(array);
   
   for(int i = 0; i < ArraySize(array); i++){
      Print("  ", i, "  array[i] = ", array[i]);
   }

   return(0);
}


double myFunction( double& theArray[]){
   
   for(int i = 0; i < ArraySize(theArray); i++){
      theArray[i] = i+10;
   }
   return(theArray);
}


2009.05.24 04:04:38 test AUDCHF,H1:   9  array[i] = 19
2009.05.24 04:04:38 test AUDCHF,H1:   8  array[i] = 18
2009.05.24 04:04:38 test AUDCHF,H1:   7  array[i] = 17
2009.05.24 04:04:38 test AUDCHF,H1:   6  array[i] = 16
2009.05.24 04:04:38 test AUDCHF,H1:   5  array[i] = 15
2009.05.24 04:04:38 test AUDCHF,H1:   4  array[i] = 14
2009.05.24 04:04:38 test AUDCHF,H1:   3  array[i] = 13
2009.05.24 04:04:38 test AUDCHF,H1:   2  array[i] = 12
2009.05.24 04:04:38 test AUDCHF,H1:   1  array[i] = 11
2009.05.24 04:04:38 test AUDCHF,H1:   0  array[i] = 10
 

here is my solution:

MT4:

#import "FXdeltaMT4DLL.dll"
     double regression(double x[], double y[], int xdim, int ySize, double params[], double intercept);
#import
nt init(){
   //---- indicators
   SetIndexStyle( 0, DRAW_LINE, 0, 1, Red);
   SetIndexLabel( 0, "Sample Debug" );  
   double x[9];
   double y[9];
   double intercept=1.0;
   int i=0;
   while(i<9){
      x[i]=i;
      i++;
   }
   y[0]=0;
   y[1]=2;
   y[2]=2;
   y[3]=3;
   y[4]=6;
   y[5]=5;
   y[6]=6;
   y[7]=16;
   y[8]=20;
   string s;
   s="Everything OK darlin'.";
   //s=GetStringValue("j");
   Hello(s,x);
   regressionWithInfo(x, y, 1, 9, intercept);
   
   double xx[18];
   i=0;int j=0;
   while(i<9){
      xx[i]=i;
      i++;
   }
   while(i<18){
      xx[i]=j*j;
      i++;j++;
   }
   regressionWithInfo(xx, y, 2, 9, intercept);
   double params[3];//container for output parameters of regression
   regression(xx, y, 2, 9, params, intercept);//compute
   Print("params0:"+params[0]);
   Print("params1:"+params[1]);
   Print("params2:"+params[2]);

C++:

FXDELTADLL_API double * __stdcall FXfunc::CFXdeltaDLL::regression(double *xdbl, double *ydbl, int xdim, int ySize, double *params, double intercept){
        
        std::vector<Array> x(ySize,xdim);
        std::vector<Real> y(ySize);
        int n=0;
        int col=0;
        do{
                col=(int)(n/ySize);
                x[n-col*ySize][col]=*xdbl++;
                n++;
        }while(n<ySize*xdim);

        n=0;
        do{
                y[n]=(*ydbl++);
                n++;
        }while(n<ySize);

        MyQuantlibLinearRegression * lr=new MyQuantlibLinearRegression(x,y,intercept);

        for(int j=0;j<lr->dim();j++){
                params[j]=lr->params(j);
        }
        
        return params;
}
 

Or ... it may not be be neccessary to return the array at all

double array[10] //declare it globaly so no need to return it

int start()
{
  myfunctionarray();
  for(int i = 0; i < ArraySize(array); i++)
   {
    Print("  ", i, "  array[i] = ", array[i]);
   }
  return(0)
}

void myfunctionarray()
(
  ArrayInitialize(myarray,0);
  //do array stuff
  return;
}
 
SDC:

Or ... it may not be be neccessary to return the array at all

That limits the functionality of the Function to a single array.
 

Yes it does, but then I did say it may not be neccessary, not that it is never neccessary ;) Having said that, it wouldnt be difficult to pass parameters to a simalar function to make it work with other global arrays.

 
phy:

Like this:

Thanks phy! Much appreciated..
 
mql4_rulez: is it possible to give an array as a return value, like this? 
double[] function23(...)
No but you can do this
double result[]; function23(result...);
:
void function23(double& result[]...){ ArrayResize(result,...); ... }
See Could EA Really Live By Order_History Alone? - MQL4 forum
 
phy:


//+------------------------------------------------------------------+
//| script program start function                                    |
//+------------------------------------------------------------------+
int start(){
   double array[10];
  
   myFunction(array);
   
   for(int i = 0; i < ArraySize(array); i++){
      Print("  ", i, "  array[i] = ", array[i]);
   }

   return(0);
}


double myFunction( double& theArray[]){
   
   for(int i = 0; i < ArraySize(theArray); i++){
      theArray[i] = i+10;
   }
   return(theArray);
}

 


If i use you example I get an error message at the point where the function is supposed to return the Array. That error says "Invalid array access"

 

can you help me with this? 

12
New comment
Reason: