Serial Print, String And Variable On Same Line

Question

How can I print to the serial monitor a string or just single character followed by a variable like "L 55"

• jfpoilpret: Read the Arduino docs for Serial.print.

Answer 1

int Var = 55;
//Do it in 2 lines e.g.
Serial.print("L "); // String
Serial.println(Var); // Print Variable on same line then send a line feed

Answer 2

For debug printing, you can define a macro to print both the name and value of a variable like this:

#define PRINTLN(var) Serial.print(#var ": "); Serial.println(var)

which you then use like this:

int x = 5;
PRINTLN(x);
// Prints 'x: 5'

---

Also this is nice:

#define PRINT(var) Serial.print(#var ":\t"); Serial.print(var); Serial.print('\t')
#define PRINTLN(var) Serial.print(#var ":\t"); Serial.println(var)

when used in a loop like so

PRINT(x);
PRINT(y);
PRINTLN(z);

prints an output like this:

x: 3 y: 0.77 z: 2
x: 3 y: 0.80 z: 2
x: 3 y: 0.83 z: 2

Answer 3

Thanks a lot for your answers. I made this ...

#define DEBUG //If you comment this line, the functions below are defined as blank lines.
#ifdef DEBUG //Macros 
 #define Say(var) Serial.print(#var"\t") //debug print, do not need to put text in between of double quotes
 #define SayLn(var) Serial.println(#var) //debug print with new line
 #define VSay(var) Serial.print(#var " =\t"); Serial.print(var);Serial.print("\t") //variable debug print
 #define VSayLn(var) Serial.print(#var " =\t"); Serial.println(var) //variable debug print with new line
#else
 #define Say(...) //now defines a blank line
 #define SayLn(...) //now defines a blank line
 #define VSay(...) //now defines a blank line
 #define VSayLn(...) //now defines a blank line
#endif

• Edgar Bonet: if (some_condition) VSayLn(some_var); won't work as intended. The standard fix is to #define VSayLn(var) do { Serial.print(#var " =\t"); Serial.println(var); } while (0). C.f. Why use apparently meaningless do-while and if-else statements in macros?