How to put boost::multi_array in initialization list of constructor?

Question

I've got a templated class mostly dedicated to holding a boost:: multi_array. I am trying to initialize the array in the initialization class, but I am getting an error:

template <typename T>
class Hist2D
{
private:
  typedef boost::multi_array<T, 2> array_type;
  array_type MatrixCount;

public:
  Hist2D(int width, int height): array_type MatrixCount(boost::extents[width][height]){}; 
};

This gives the following error:

ctest.cpp: In constructor ‘Hist2D<T>::Hist2D(int, int)’:
ctest.cpp:34:45: error: expected ‘(’ before ‘MatrixCount’
   Hist2D(int width, int height): array_type MatrixCount(boost:extents[width][height]){}; 
                                             ^
ctest.cpp:34:45: error: expected ‘{’ before ‘MatrixCount’

What do these errors mean?

The error means you're trying to invent syntax of your own. If you replaced array_type MatrixCount; with int MatrixCount;, would this make sense? Hist2D() : int MatrixCount(10) {} — Praetorian
– Praetorian, Commented Jul 16, 2015 at 22:35

Praetorian · Accepted Answer · 2015-07-16 22:36:57Z

3

It is a syntax error. You do not need to declare the type in the initialization list.

Try this:

Hist2D(int width, int height): MatrixCount(boost::extents[width][height]){}

C++ compilation errors can be confusing. You'll get used to them after a while :D

edited Jul 16, 2015 at 22:36

Praetorian

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answered Jul 16, 2015 at 22:31

brettwhiteman

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2 Comments

brettwhiteman Over a year ago

@Praetorian thanks for the fix up, didn't spot those mistakes

sunny Over a year ago

Yup, I always find that the toughest part of learning a new language, and C++ does seem more confounding than others. Thanks a lot.

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