you need to take 2 (hex) chars at the same time... then calculate the int value and after that make the char conversion like...
char d = (char)intValue;
do this for every 2chars in the hex string
this works if the string chars are only 0-9A-F:
#include <stdio.h>
#include <string.h>
int hex_to_int(char c){
int first = c / 16 - 3;
int second = c % 16;
int result = first*10 + second;
if(result > 9) result--;
return result;
}
int hex_to_ascii(char c, char d){
int high = hex_to_int(c) * 16;
int low = hex_to_int(d);
return high+low;
}
int main(){
const char* st = "48656C6C6F3B";
int length = strlen(st);
int i;
char buf = 0;
for(i = 0; i < length; i++){
if(i % 2 != 0){
printf("%c", hex_to_ascii(buf, st[i]));
}else{
buf = st[i];
}
}
}
you need to take 2 (hex) chars at the same time... then calculate the int value and after that make the char conversion like...
char d = (char)intValue;
do this for every 2chars in the hex string
this works if the string chars are only 0-9A-F:
#include <stdio.h>
#include <string.h>
int hex_to_int(char c){
int first = c / 16 - 3;
int second = c % 16;
int result = first*10 + second;
if(result > 9) result--;
return result;
}
int hex_to_ascii(char c, char d){
int high = hex_to_int(c) * 16;
int low = hex_to_int(d);
return high+low;
}
int main(){
const char* st = "48656C6C6F3B";
int length = strlen(st);
int i;
char buf = 0;
for(i = 0; i < length; i++){
if(i % 2 != 0){
printf("%c", hex_to_ascii(buf, st[i]));
}else{
buf = st[i];
}
}
}
Few characters like alphabets i-o couldn't be converted into respective ASCII chars . like in string '6631653064316f30723161' corresponds to fedora . but it gives fedra
Just modify hex_to_int() function a little and it will work for all characters. modified function is
int hex_to_int(char c)
{
if (c >= 97)
c = c - 32;
int first = c / 16 - 3;
int second = c % 16;
int result = first * 10 + second;
if (result > 9) result--;
return result;
}
Now try it will work for all characters.
This worked for me.
$ echo -n 54657374696e672031203220330 | xxd -r -p
Testing 1 2 3$
echo -n prevents a newline from being added to the end
-r tells it to convert hex to ascii as opposed to its normal mode of doing the opposite
-p tells it to use a plain format.
This code will convert the text 0xA7.0x9B.0x46.0x8D.0x1E.0x52.0xA7.0x9B.0x7B.0x31.0xD2 into a stream of 11 bytes with equivalent values. These bytes will be written to standard out.
TESTDATA=$(echo '0xA7.0x9B.0x46.0x8D.0x1E.0x52.0xA7.0x9B.0x7B.0x31.0xD2' | tr '.' ' ')
for c in $TESTDATA; do
echo $c | xxd -r
done
As others have pointed out, this will not result in a printable ASCII string for the simple reason that the specified bytes are not ASCII. You need post more information about how you obtained this string for us to help you with that.
How it works: xxd -r translates hexadecimal data to binary (like a reverse hexdump). xxd requires that each line start off with the index number of the first character on the line (run hexdump on something and see how each line starts off with an index number). In our case we want that number to always be zero, since each execution only has one line. As luck would have it, our data already has zeros before every character as part of the 0x notation. The lower case x is ignored by xxd, so all we have to do is pipe each 0xhh character to xxd and let it do the work.
The tr translates periods to spaces so that for will split it up correctly.