C++ syntax doubts

[tcsvikr]

consider the code given below:

class base { //line1
private: //line2
const int a; //line3

public: //line4
base(int val = 0) : a(val) {} //line5
int get_a() { return a; }
}; // C4512 warning

class base2 {
private:
const int a;

public:
base2(int val = 0) : a(val) {}
base2 & operator=( const base2 & ) {}
int get_a() { return a; }
};

int main() {
base first;
base second;

// OK
base2 first2;
base2 second2;
}


What does the 'line5' signify?..I think ':' operator is for deriving a class from base class. But what is it doing for a method? I really could not understand .Can anyone help me???

[bagapriya]

consider the code given below:

class base { //line1
private: //line2
const int a; //line3

public: //line4
base(int val = 0) : a(val) {} //line5
int get_a() { return a; }
}; // C4512 warning

class base2 {
private:
const int a;

public:
base2(int val = 0) : a(val) {}
base2 & operator=( const base2 & ) {}
int get_a() { return a; }
};

int main() {
base first;
base second;

// OK
base2 first2;
base2 second2;
}


What does the 'line5' signify?..I think ':' operator is for deriving a class from base class. But what is it doing for a method? I really could not understand .Can anyone help me???

STATEMENTS COMING AFTER // IS USER FRIENDLY COMMENTS......

[horace1]

this is a constructor

base(int val = 0) : a(val) {} //line5

where : a(val) is an initialisation list which initialises the data member a to the value of parameter val (which will default to 0 if non is supplied) see
http://www.cprogramming.com/tutorial/initialization-lists-c++.html