to convert int to hex Post: 302152328

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Top Forums Programming to convert int to hex Post 302152328 by DreamWarrior on Wednesday 19th of December 2007 03:35:19 PM

12-19-2007

Registered User

Quote:

Originally Posted by WebKruncher

#include <string>
#include <sstream>
using namespace std;

//This spends some extra cycles, offers simplicity, elegance and safety.
string IntToHexString(int i)
{
stringstream ss;
ss<<"0x"<<hex<<i;
string retval; retval=ss.str().c_str();
return retval;
}

//usage
cout<<"Hex for 32 is "<<IntToHexString(32)<<endl;
// as always handle your seh exceptions with a try / catch.

Correct me if I am wrong, but it also either 1) leaks memory, 2) reads a wild pointer, or 3) is thread unsafe:

Logically:

The .c_str call must return a "string".

Given:

A string is a pointer to a "NULL terminated string."

A "NULL terminated string" is a sequence of characters terminated by a '\0' character; we shall call this a "buffer".

A buffer resides somewhere in memory.

Therefore:

The .c_str call must return a pointer a buffer containing its contents.

In order not to leak, the above buffer must be freed at some point. To be freed the buffer must still referenced. Since the caller of IntToHexString does not take a reference then to not leak, either a) someone else must free it or b) someone else has a reference to it.

If (a) then the "somewhere" else may be the destructor of stringstream class. I presume this destructor is called when the stack for your function is cleaned up. This means that the string returned by IntToHexString becomes "wild" as soon as it returns.

If (b) then the buffer can be overwritten at some point by the class still holding a reference to it and therefore can not be thread safe.

If neither a nor b occurs then the code leaks. The only way this is untrue is if the compiler takes care of destroying the string returned by IntToHexString.

DreamWarrior

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LEARN ABOUT DEBIAN

netsds::util::convert

NetSDS::Util::Convert(3pm)				User Contributed Perl Documentation				NetSDS::Util::Convert(3pm)

NAME

       NetSDS::Util::Convert - data formats conversion functions

SYNOPSIS

	       use NetSDS::Util::Convert qw(...);

DESCRIPTION

       "NetSDS::Util::Convert" module contains miscelaneous functions.

       o   CLI parameters processing

       o   types validation

       o   HEX, Base64, URI, BCD encondig

       o   UUID processing

EXPORTED FUNCTIONS

       conv_conv_str_bcd($str) - convert string to little-endian BCD
	   This function converts string to little-endian BCD encoding filled with F16 value.

       conv_chr_hex($char) - encode char to hexadecimal string
		   $hex = conv_chr_hex('a'); # return 61

       conv_hex_chr($hex) - convert hexadecimal string to character
		   $chr = conv_hex_chr('4A'); # return 'J'

       conv_str_hex($str) - convert byte string to hexadecimal
		   $str = 'Want hex dump!';
		   $hex = conv_hex_str($str);
		   print "Hex string: " . $hex;

       conv_hex_str($string) - convert hex to byte string
		   $hex = '7A686F7061';
		   $string = conv_hex_str($hex);
		   print "String from hex: " . $string;

       conv_str_base64($str) - convert string to Base64
		   my $b64 = str_base64("Hallo, people!");

       conv_base64_str($b64) - convert Base64 to string
		   my $str = base64_str($base64_string);

       conv_str_uri($str) - convert string to URI encoded
	   Example:

		   my $uri = str_uri("http://www.google.com/?q=what");

       conv_uri_str($uri) - decode URI encoded string
	   Example:

		   my $str = uri_str($uri_string);

EXAMPLES

       None

BUGS

       None

TODO

       1. Add other encodings support

SEE ALSO

       Pod::Usage, Data::UUID

AUTHORS

       Valentyn Solomko <pere@pere.org.ua>

       Michael Bochkaryov <misha@rattler.kiev.ua>

perl v5.12.4							    2011-08-27						NetSDS::Util::Convert(3pm)

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