Convert a char string to hex

Kookoo · Guest

Hello,

is there any function to convert a char string of 2 characters for example : char test[1]

to an hexadecimal number : byte hex ?

Many Thanks.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Here's how to find the answer:
Look at the chart of built-in functions on page 98 (in the Acrobat reader)
of the CCS manual. It has a list of standard string handling or
character handling functions. At the top of the chart, it lists functions
such as atoi, atol, etc. These mean "ASCII to integer", etc.

The source code for these functions is in stdlib.h, which is in this folder:
c:\Program Files\PICC\Drivers

If you think those functions have too much code, there are truncated
versions posted in various places on the forum:
http://www.ccsinfo.com/forum/viewtopic.php?t=17563&highlight=adtol

mdares · Joined: 26 Oct 2005 Posts: 19

You can just cast a character to it's ascii value using (int), but you didn't look very hard if your asking this question.

Mattd

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

If he has an array of two characters, such as "15", the array consists
of two ASCII bytes, 0x31 and 0x35.

I assume he wants to convert that number to an integer: 0x0F

You can't do that by casting.

newguy · Joined: 24 Jun 2004 Posts: 1909

I do this with something I built. I have to download hex codes to an on-board I2C EEPROM via RS232.

Unless you convert lowercase ascii letters (a-f) to uppercase before you do this conversion, it will fail. I simply make sure the caps lock key is on before I do my downloads.

I use this function with a interrupt-driven serial receive routine, very similar to what has been posted on this board dozens of times.

All the code does is search through the received data buffer and converts the ascii digits 0-9 and a-f into their hex equivalents, 0 - 15. It then does a second pass through the data, taking pairs of characters and combining them into one 8 bit value. You should be able to follow it.

mdares · Joined: 26 Oct 2005 Posts: 19

I see, I think your right PCM, I was going on he char test[1] as what he wants to 'convert'. eg

for i = 1 to n {
some_int[i] = (int) some_char[i]
}

Kookoo · Guest

Hello,

i have to get the date and time for example :

char year[2];
char month[2];
char date[2];

printf("\n\rYear : ");
gets(year);
printf("\n\rMonth : ");
gets(month);
printf("\n\rDate : ");
gets(date);

For example, if i put :

06
01
18

I will have :
year[0] => 0
year[1] => 6
month[0] => 0
month[1] => 1
date[0] = > 1
date[1] = > 8

I have a real time clock that i want to initialize with this function :

RTC_set_datetime(date, month, year, hour, min, sec);

But this function take bytes in parameters, and i have char strings.
It should be like this :

RTC_set_datetime(18, 01, 06, 10, 58, 00);

for 2006/01/18 10:58:00

How can i do this ?

Thanks !

Kookoo · Guest

I used atoi function with something pretty much like this :

year= atoi(year_char, 16);

It works very well.
Thanks a lot.