Question

I need a piece of c# snippet explained

while (read_Email.Read())
{
email = read_Email.GetValue(i).ToString();
list_emails.Add(email);
i = i + 1 - 1;

}

what does the i = i + 1 - 1; mean? I know of +=, but i++,++i part is puzzling

Answer 1

Provided snippet of code reading from email values with index of i.

i = i + 1 - 1; // This one is doing nothing. (variable i doesn't change it's value at every iteration)

What about difference between i++ and ++i:
Each of them is iteration of variable.
i++ gives same result as i = i + 1 or i += 1;
++i gives same result with only one difference: CALCULATION of it will be done before variable i will be getted or returned.
This means for example:
void Main()
{
int i;
Console.WriteLine(GetIteration(out i));
Console.WriteLine(i);
}
public int GetIteration(out int i)
{
i = 4;
return i++;
}
Result of this code above will be:
4
5
--------------------------------------------------------------
void Main()
{
int i;
Console.WriteLine(GetIteration(out i));
Console.WriteLine(i);
}
public int GetIteration(out int i)
{
i = 4;
return ++i;
}

Result of this code above will be:
5
5
--------------------------------------------------------------
So, as you can see returned variable at second option was incremented before it was returned to invocation method.