C++ Program to Find 1’s Complement of a Binary Number

#include<iostream.h>
#include<conio.h>
using namespace std;
class test
{
string sk;
public:
void read(void)
{
cout<<"Enter the Binary Number:"; cin>>sk;
}
void bin_num(void)
{
for(int i=0;i<sk.length();i++)
{
if(sk.at(i)!='0' && sk.at(i)!='1')
{
cout<<"Incorrect binary number!"
getch();
exit(0);
}
}
}
void binary(void)
{
bin_num();
for(i=0;i<sk.length();i++)
{
if(sk.at(i)=='0')
sk.at(i)='1';
else
sk.at[i]='0';
}
}
void display(void)
{
binary();
cout<<"The 1's Complement of this Binary Number is :"<<sk;
}
};
int main()
{
test t1;
t1.read();
t1.display();
getch();
return 0;
}

Enter the Binary Number: 101101
The 1's Complement of this Binary Number is : 010010