Hello,

I tried already different variations of statements for the function parameter, but I still do not have the right version of it. I have got a function pointer and want to pass it as function parameter. Please tell me what is the right usage of it?

Qt Code: 
  1. class SpectrogramData: public QwtRasterData
  2. {
  3. public:
  4.     SpectrogramData(double (*b)(double, double), double rang1[2],  double rang2[2]):
  5.         QwtRasterData(QwtDoubleRect(rang1[0], rang2[0], rang1[1]- rang1[0], rang2[1]- rang2[0]))
  6.     {
  7.     	benchFunc = b;
  8.     	rangeX1[0] = rang1[0];	rangeX1[1] = rang1[1];
  9.     	rangeX2[0] = rang1[0];	rangeX2[1] = rang2[1];
  10.     }
  11.  
  12.     virtual QwtRasterData *copy() const
  13.     {
  14.         return new SpectrogramData( benchFunc , &rangeX1[2], &rangeX2[2]);   //<<< << this is the reason for the error
  15.     }
  16.  
  17.     virtual QwtDoubleInterval range() const
  18.     {
  19.         return QwtDoubleInterval(0.0, 10.0);
  20.     }
  21.  
  22.     virtual double value(double x, double y) const
  23.     {
  24.  
  25.     	const double result = benchFunc(x,y);
  26.         return result;
  27.     }
  28.  
  29. private:
  30. 	double (*benchFunc)(double, double);	// function pointer
  31. 	double rangeX1[2];
  32. 	double rangeX2[2];
  33. };
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error:
Compiling ./qt/plot.cpp
plot.cpp: In constructor 'SimpleData::SimpleData(double, double, double)':
plot.cpp:60: warning: passing 'double' for argument 1 to 'int abs(int)'
plot.cpp: In member function 'virtual QwtRasterData* SpectrogramData::copy() const':
plot.cpp:109: error: no matching function for call to 'SpectrogramData::SpectrogramData(double (* const*)(double, double), const double*, const double*)'
plot.cpp:99: note: candidates are: SpectrogramData::SpectrogramData(double (*)(double, double), double*, double*)
plot.cpp:97: note: SpectrogramData::SpectrogramData(const SpectrogramData&)
make[1]: *** [../obj/linux-amd64-gcc-lsb31/plot.o] Error 1
make: *** [obj_qt] Error 2