Arduino data type confusion. Have string, need const char?

Question

I'm working with an UNO and I'm using maniacbug's RF24 library with soft spi, and his rf24network library. https://github.com/maniacbug/RF24Network

All I'm trying to do is send data but I'm stuck with the wrong data type.

{
last_sent = now;

printf("Sending...\r\n");
const char* hello = "Hello, world!";
RF24NetworkHeader header(/*to node*/ other_node);
bool ok = network.write(header,hello,strlen(hello));
if (ok)
  printf("\tok.\r\n");
else
{
  printf("\tfailed.\r\n");
  delay(250); // extra delay on fail to keep light on longer
}
}

If I change it to

bool ok = network.write(header,myString,strlen(myString));

I get an error on data type. So how do I get my string to fit this structure. My thought was to to a myString.toCharArray then maybe loop through that?

Answer 1

Convert the String into a char array first:

size_t len = myString.length();
char buf[len+1]; // +1 for the trailing zero terminator
myString.toCharArray(buf, len);

and then you can pass buf:

bool ok = network.write(header,buf,strlen(buf));