Serial string sum comparison

Projects Programming
4

Thank you for your help! But I got the following message on the code when trying to compile your example:

error line: printf (" %4s %4s %4d\r", comrx, s, strcmp (comrx, s));

cannot convert 'String' to 'const char*' for argument '1' to 'int strcmp(const char*, const char*)'

if(Serial.available() > 0)
{
comrx = Serial.readStringUntil('\r');
Serial.println(comrx);

for (int i = 0; i <= 15; i++)  
 {
  char s [10];
  sprintf (s, "TO%d\r", i);
  printf (" %4s %4s %4d\r", comrx, s, strcmp (comrx, s));
 }

int  n;
sscanf (comrx, "TO%d", & n);
Serial.print (n,HEX);

return 0;

}