how to declare a variable as a calendar date

[sja3l]

i want to make a program like this

unsigned int y, m, d;
//char a [3]={y,m,d};
//char b [3]={y,m,d};
cout<<"Insert data a: "; cin>>a; //like yyyy mm dd
cout<<"Insert data b: "; cin>>b; //like yyyy mm dd
cout<<(a+b)/2;

but using the <time.t> library