string with hex value to byte

[ardugebruiker]

how to convert string to byte ?

eg : string "60" to byte 0x60
eg : string "a5" to byte 0xa5

thx in advance

[christop]

Use strtoul(). Set the base to 16, and you can just pass in NULL for the endptr argument, like so:

char s[] = "60";
byte b = strtoul(s, nullptr, 16);
// b is now 0x60

[ardugebruiker]

okay and how to convert string to char[] ?

eg

String a = "60" ;

to ...

[ardugebruiker]

String test = "60";
char charbuf[2];
test.toCharArray(charbuf, 8);
byte b = strtoul(s, nullptr, 16);


---error = exit status 1
's' was not declared in this scope

[anon73444976]

char charbuf[2]; is not big enough to contain your string

[christop]

You don't need to copy the String to a string. Use c_str() to get to the String's internal string buffer:

String test = "60";
byte b = strtoul(test.c_str(), nullptr, 16);