problem with a reverse iterator

[brad]

In the example below, possible_number is a string of one or more
digit(s). For example, it may be 4 or 4444. However, when I attempt to
perform the times 2 calculation, the ASCII value of 4 (which is 52) is
used instead of 4 itself. I need to be able to easily reverse the order
of the digits and to only perform this calculation on even positioned
digits... that's why I'm using string instead of int. Any suggestions on
how to make 4*2 = 8 I've tried atoi() type casting, etc. I'm stuck.
Still learning c++.

Thanks for any help!

int position = 0;

string::reverse_iterator rit;
for (rit=possible_number.rbegin(); rit < possible_number.rend(); rit++)
{
if (position % 2 == 0)
{
// Here's the problem *rit * 2 = 104, not 8
cout << position << *rit * 2 << endl;
position++;
}
}

 

[brad]

An element of a string is of type 'char'. As you have found out
already, the value is controlled by the encoding of the symbol.
If you want to convert a char that supposedly contains a decimal
digit into its corresponding number, you need to (a) test to see
that it's actually a digit (see 'isdigit' function) and (b) if it
is a digit, subtract '0' from it:


if (isdigit(*rit))
cout << position << (*rit - '0') * 2 << endl;
else
cerr << position << " - not a digit!!!" << endl;


V

Wow. That works. I do not fully understand why it works, but I wanted to
thank you for the advice. I'll research it more until I better understand.

Brad