Why is the compiler giving an error???

Question

#include <iostream>
using namespace std;
class Human {

int cnic;
int age;
public:
int setdata(int ,int );/*{
a= cnic;
b=age;
}*/
void getdata(){
cout<<"My CNIC is "<<cnic<<endl;
cout<<"My age is "<<age<< endl;
}
};
int Human::setdata(int a,int b){
a= cnic;
b=age;
}
class student :public Human{
int rollno;
int section;
public:
int setdata(int x ,int y){
x=rollno;
y=section;
}
void getdata(){
cout<<"My roll no. is "<<rollno<<endl;
cout<<"My section is "<<section<<endl;
}
};
class Employee :public Human{
string name;
int id;
public :
int setdata(string ,int );/*{
o1=name;
o2=id;
}*/
void getdata(){
cout<< "Employee ID is "<<id <<endl;
cout<<"Employee name is "<<name<<endl;
}
};
int Employee ::setdata(string o1 ,int o2){
o1=name;
o2=id;
}

int main() {
Human h;
h.setdata(123,34);
h.getdata();
return 0;

Answer 1

setters should have void return type.
Also you have arguments and variables reversed.

Answer 2

#include <iostream>
using namespace std;
class Human {
int cnic;
int age;
public:
void setdata(int a, int b){
cnic = a;
age = b;
}
void getdata(){
cout<<"My CNIC is "<<cnic<<endl;
cout<<"My age is "<<age<< endl;
}
};

class Student :public Human{
int rollno;
int section;
public:
void setdata(int x ,int y){
rollno = x;
section = y;
}
void getdata(){
cout<<"My roll no. is "<<rollno<<endl;
cout<<"My section is "<<section<<endl;
}
};

class Employee :public Human{
string name;
int id;
public :
void setdata(string o1 ,int o2){
name = o1;
id = o2;
}
void getdata(){
cout<< "Employee ID is "<<id <<endl;
cout<<"Employee name is "<<name<<endl;
}
};

int main() {
Human h;
h.setdata(123,34);
h.getdata();

Student s;
s.setdata(30,5);
s.getdata();

Employee e;
e.setdata("Shamir", 455);
e.getdata();
}