# convert hex string to decimal

Discussion in 'C Programming' started by Gospill, Mar 27, 2005.

1. ### GospillGuest

Hi Guru,

If I have string like "0D76" for example, it is actually a 0x0D76 in hex
format.
How can I convert the hex string 0D76 into decimal value ? So that I will
get decimal value 3446

Thanks.

Gospill, Mar 27, 2005

2. ### Martin AmbuhlGuest

Gospill wrote:
> Hi Guru,
>
> If I have string like "0D76" for example, it is actually a 0x0D76 in hex
> format.
> How can I convert the hex string 0D76 into decimal value ? So that I will
> get decimal value 3446

Please check the FAQ and archives before posting.
#include <stdlib.h>
#include <stdio.h>

int main(void)
{
char s[] = "0D76";
unsigned long x;
x = strtoul(s, 0, 16);
printf("The value represented by the string \"%s\" is\n"
"%lu (decimal)\n" "%#lo (octal)\n" "%#lx (hex)\n",
s, x, x, x);
return 0;
}

[output]
The value represented by the string "0D76" is
3446 (decimal)
06566 (octal)
0xd76 (hex)

Martin Ambuhl, Mar 27, 2005

3. ### Barry SchwarzGuest

On Sun, 27 Mar 2005 16:15:57 +0800, "Gospill" <>
wrote:

>Hi Guru,
>
>If I have string like "0D76" for example, it is actually a 0x0D76 in hex

"0D76" is a string. It occupies five char.

0x0D76 is not a string. It occupies at most 2 bytes.

Don't confuse the two and please try not to confuse us by introducing
completely extraneous data. You either want to process the first or
the second. I assume form actually you want to deal with the second.

>format.
>How can I convert the hex string 0D76 into decimal value ? So that I will
>get decimal value 3446
>

Where is your hex value? Where do you want the result stored?

If your hex value is already in a variable of integer type, then any
member of the printf family will do the trick.

If your hex value is not already in an array of unsigned char, you
need to get it there (memcpy if in memory, fread if in a file, etc).

Once you get it there, you need to process each hex digit (also known
as a nybble) in turn and accumulate the result in an integer of some
type. Assuming CHAR_BIT is 8 on your system, a function like the
following should get you started:

int hex_to_int(unsigned char hex[], int count)
{
int sum = 0;
int i;
int temp;

for (i = 0; i < count; i++)
{
temp = (hex & 0xf0U) >> 4;
sum = sum*16 + temp;
temp = (hex & 0xofU);
sum = sum*16 + temp;
}
return sum;
}

<<Remove the del for email>>

Barry Schwarz, Mar 27, 2005
4. ### Chris CroughtonGuest

On Sun, 27 Mar 2005 16:15:57 +0800, Gospill
<> wrote:

> If I have string like "0D76" for example, it is actually a 0x0D76 in hex
> format.

I presume you mean that it is currently a character string and you want
it as a binary value?

> How can I convert the hex string 0D76 into decimal value ? So that I will
> get decimal value 3446

Look up strtol() in your reference book.

#include <stdlib.h>
#include <stdio.h>

int main(void)
{
char string[] = "0D76";
long value = strtol(string, NULL, 16);
printf("value of '%s' is %ld\n", string, value);
return 0;
}

Chris C

Chris Croughton, Mar 27, 2005