a little bit offtopic: c++ question in kdevelop-tutorial

[Richard Moore]

AndiX33 at aol.com wrote:
> 
> hello,
> 
> while reading the tutorials shipped with kdevekop, i´ve read an example i
> don´t understand. and i hope that within this list there are people skilled
> an experienced in programming.
> 
> the example:
> 
>  .....
> 1       class Math:
> 2       {
> 3       public:
> 4       //Constructor contains definition of PI
> 5       Math ():  PI (3,142) {}
> 6       ~Math () {}
> 7       float  diameter (float radius)
> 8       {
> 9       return ( radius * PI )
> 10      }
> 11      private:
> 12      // declare PI. we cann´t assign a value
> 13      const float PI
> 14      }
> 
> what does the ":" in line 4?? is it a kind of operator or what does it
> it seems strange to me and i didn´t find a solution in books.
> why you don´t write:

It calls the constructor for the constant. Obviously this isn't really
needed for a float, but it is generally good style to do this (it would
be required if it was a reference to an object with no default constructor).
IIRC according to the C++ standard this is the recomended way to initialise
a constant member in any case. Note that it would better code if the constant
was static anyway and better still if it used the constant defined in math.h.

Rich.

> 
> Math::Math ()
> {
>    pi=3,142;
> }
> 
> greetings
> andreas schmitzer
> 

-- 
     Richard Moore		rich at ipso-facto.freeserve.co.uk
http://www.robocast.com/	richard at robocast.com
http://developer.kde.org/	rich at kde.org