Credit Card Validation

Question

This one seemed to be easy at first, but i found myself stuck with this coad coach) could anyone help me out?
https://www.sololearn.com/coach/96?ref=app

Answer 1

The first big problem you have is in converting of input into integer. Better will be to code:
b[i] = Convert.ToInt32(Convert.ToString(a[i]));

The second are the length of the for loops. Only the first for loop counts till end of your array.

Answer 2

namespace Sololearn
{
class Program
{
static void Main(string[] args)
{
//1— turned string to int[]+ made a reverse
string a =Console.ReadLine();
if (a.Length==16)
{
int [] b = new int [16];
int count =0;
for (int i=0;i<=15;i++)
{
b[i] = (int)Char.GetNumericValue(a[15-i]);
}
//2 - doubled all the odd numbers
for (int j=0;j<15;j+=2)
{
b[j]*=2;
}
for (int m =0;m<15;m++)
{
if (b[m]>9) // made a sum with a 9 substraction
{
b[m]-=9;
count+=b[m];
}
else
{
count+=b[m];
}
}
// sum validation and String Length validation
if (count%10==0)
{
Console.WriteLine("valid");
}
else
{
Console.WriteLine("not valid");
}
}
else
{
Console.WriteLine("not valid");
}
}
}
}