lcd.print then dataFile.print

Question

My program is a bit large and I'm worried about stability.

I need to print data to both a file and to my LCD. It's like this:

if (hour<10) {
 dataFile.print("0");
}
dataFile.print(hour, DEC);
dataFile.print(":");
if (minute<10) {
 dataFile.print("0");
}
dataFile.print(minute, DEC);
dataFile.print(":");
if (second<10) {
 dataFile.print("0");
}

Then

if (hour<10) {
 lcd.print("0");
}
lcd.print(hour, DEC);
lcd.print(":");
if (minute<10) {
 lcd.print("0");
}
lcd.print(minute, DEC);
lcd.print(":");
if (second<10) {
 lcd.print("0");
}

What is a smart way to make this shorter? Should I write a function to add the leading zero then another that does something like:

void printboth (thing) {
 dataFile.print(thing);
 lcd.print(thing);
}

good idea?

• Nick Gammon: possible duplicate of What will use less memory, an array or if ... else?
• Nick Gammon: You asked an almost identical question here: arduino.stackexchange.com/questions/13876/… where you start: I'm trying to make my sketch smaller. Please stick to one question for one topic to avoid splitting answers.
• Gerben: Give __attribute__((always_inline)) void printboth (thing) a try and see if it results in a smaller size. PS make sure you are using the latest version of the Arduino IDE.

Answer 1

You could format the data with snprintf:

char timestamp[9];
snprintf(timestamp, 9, "%02d:%02d:%02d", hour, minute, second);
dataFile.print(timestamp);
lcd.print(timestamp);

%02d in the snprintf format means "print at least 2 digits of this value and pad with leading zeros".

• Ignacio Vazquez-Abrams: While true, note that *printf() will increase code size a lot.
• Majenko: Define "a lot". I make it an increase of 1046 bytes and the program is far more readable.
• futurebird: I'm making changes with the main goal of making the sketch smaller