Notes

public class LAB_1_16DECEMBER_22DECEMBER_2019
{
public static void main ()
{
int num = 2315778;
System.out.println("Credit card number: " + num + " is " + checkDigits(num));
num = 1234567;
System.out.println("Credit card number: " + num + " is " + checkDigits(num));
num = 7654321;
System.out.println("Credit card number: " + num + " is " + checkDigits(num));
num = 1111111;
System.out.println("Credit card number: " + num + " is " + checkDigits(num));
// Put your code here }

}
public static String checkDigits (int a)
{
String name = "invalid" ;
String b = a+"";
int length = b.length();
int length_position = length ;
System.out.println(length);
int sum = 0 ;
int remain ;
for (;length_position>0;length_position--) // position is odd
{
remain = a % 10 ;
if (length_position % 2 == 1)
{
sum = sum + remain;
}
else if (length_position% 2 == 0) // position is even
{
remain = remain *2 ;
String remain_length_str = remain+"";
int remain_length = remain_length_str.length();
if(remain_length==1)
{
sum = sum + remain;
}
else if (remain_length==2)
{
int x = remain % 10 ;
sum = sum + x;
remain = remain / 10 ;
sum = sum + remain;

}
}


a = a/10;
}
System.out.println(sum);
if (sum%10 == 0)
{
name = "valid" ;

}
else
{


}




return name ;
}
}