Delegating constructors

A constructor may call another constructor using the same member list syntax:

    class car 
    { 
        // data members 
    public: 
        car(double front, double back, double s = 25.0)  
           : tire_pressures{front, front, back, back}, spare{s} {} 
        car(double all) : car(all, all) {} 
    };

Here, the constructor that takes one value delegates to the constructor that takes three parameters (in this case using the default value for the spare).