A constructor calls another constructor of the same class?

[dullboy]

class Foo {
public:
Foo(char x);
Foo(char x, int y);
...
};

Foo::Foo(char x)
{
...
Foo(x, 0); // this line does NOT help initialize the this object!!
...
}

My questions is why Foo(x,0) doesn't help initialize the this object? Thanks for your suggestions.