valid type for default arguement of a vector in a constructor

[danielsbrewer]

Hi,

I have a constructor for class Grapher that is defined like this:


Grapher( const vector<string> & , string ="graph");

The thing is i would like to provide arguement for the vector<string> so that I have a default constructor e.g.

Grapher temp();

Anything I put in means gcc kicks up a fuss.

Any ideas?

Thanks

Daniel Brewer

[Paul McKenzie]

Why not create a default constructor and pass an empty (or whatever) vector<string> of your choice? You will need to separate the code into another function, but it will do the job.

#include <vector>
#include <string>

typedef std::vector<std::string> VecString;

class Grapher
{
    public:
        Grapher( const VecString& vs, std::string s ="graph")
        {
               InitFunc(vs, s);
        }

        Grapher( ) 
        { 
            VecString S; 
            InitFunc(S);
        }  

    protected:
        void InitFunc( const VecString& vs, std::string s="graph")
        { /* Place the body of the non-default constructor here */ }
};

Just another tip: If Grapher is defined in a header file, it looks like you used a "using namespace std" in your header file for Grapher since I see a lack of "std::" within the fle. It isn't a good idea to introduce the namespace in the header file. When you include the header in a CPP file, you are introducing the entire std:: within the CPP also, which may not be desired (the .CPP file may have a "vector" or "string" class that is different than std::vector or std::string. Your header file would mess things up).

Instead do what I did above -- explicitly state "std::" in the header file. Within the .CPP file, you can state "using namespace std:".

Regards,

Paul McKenzie