Re: Detecting hex strings

Stefan Naewe <>
Fri, 27 Jun 2008 12:37:34 +0200
On 6/26/2008 10:02 PM, Tom Walker wrote:

"goodTweetieBird" <> wrote in message

I need a function that converts ascii strings to ints. If either of
the first two characters is an 'x' or 'X' it should be handled as hex,
else base 10. I wrote the following which works but seems ineligant.
Is there a more compact and efficient way to do this? If first two
characters are 'X' then it is OK for this and other errosr to fall
thru. Also what function is used to convert ascii hex to int?

int f1(char* s)
   int i;
   sscanf(s, "%i", &i);
   return i;

sscanf with %i handles decimal and hex and octal.


Why not take a stringstream with 'dec' flag unset ?
Something like this:

bool get_int(string const& sval, int& ival)
    int result = 0;
    stringstream sstr;
    sstr << sval;
    if(sstr >> result)
        ival = result;
        return true;
    return false;

(I know it's 3 lines vs. 10 lines. But using streams is much more flexible,

Any thoughts?

Stefan Naewe stefan dot naewe at atlas-elektronik dot com
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