convert a string of hex to a char ?

Projects Programming
1

i have a string that i pass to a variable of char[5] via the serial port

i now need to copy this string/char[] to a char variable

is there a way to convert a string hex ie "0x11" to a char ?

2

You can use strtoul

3

thanks for the tip

is this the correct syntax ?

Char User1;

char cvar[5];

if (Serial.available() > 0) {
// read the incoming byte:
incomingStr = Serial.readString();

if (incomingStr.startsWith("U1D")) {
Serial.print("User1 Data");

incomingStr = (incomingStr.substring(3));
incomingStr.toCharArray(cvar, 5);

Serial.print(cvar);
Serial.println("#");

User1 = strtoul(cvar , NULL , 5);

{

4

is this the correct syntax ?

Char User1;

No.
'char' is spelled 'char'.

Please remember to use code tags when posting code

5

It looks like strtoul will not handle the "0x" prefix, so you need to pass a pointer to the string after the 'x'. The third parameter is the base, not the size. Here's my test.

void setup()
{

  const char c_number[] = "0x11";

  Serial.begin(9600);
  Serial.print("Char:  "); Serial.println(c_number); // 0x11

  unsigned long ul_number;
  ul_number = strtoul(c_number, NULL, 2);
  Serial.print("Ulong:  "); Serial.println(ul_number); // 0

  ul_number = strtoul(strchr(c_number, 'x') + 1, NULL, 2);
  Serial.print("Ulong:  "); Serial.println(ul_number);  // 3

}

void loop()
{


}
6

If you tell strtoul that the text is a base-2 representation, 0x is obviously invalid.

void setup()
{
  Serial.begin(57600);
  while(!Serial);
  
  char text[] = "0x11";
  byte number = strtoul(text, NULL, 16);

  Serial.println(number);
}

void loop()
{
}
7

thanks guys - that worked a treat

User2 = strtoul(cvar, NULL, 16);