Error with ASCII to Hex conversion

[Jeremy2016]

Hi lads

i am a newbie at C++ so i am learning slowly

i am testing the following example code to convert ASCII to Hex data but the output somehow is showing extra FFFFFFF

thats the code


// hex numbers print.cpp : main project file.

#include "stdafx.h"
#include <algorithm>
#include <iostream>

void output_hex(char ch)
{
std::cout << std::hex << int(ch);
}

int main(int argc, char **argv)
{
std::string str(">áĐ©ydQ@1$"); //ASCII data beeing converted

std::for_each(str.begin(), str.end(), output_hex);

system("PAUSE");

return 0;
}

and this is the output

1019ffffffe1ffffffc4ffffff90ffffffa9796451403124

the correct output should be
1019e1c490a9796451403124


Any ideas of whats wrong in the code ?

[kbw]

You're pass the value as a signed byte. You then cast that signed char to a signed int, with that cast.

When the high bit is set, the number is interpreted as a negative number, and that's where all those fffff things come from.

You can fix this by arranging for that function to receive an unsigned char.