Need help printing floats to LCD

Projects Programming
1

Hello, I need help with printing decimals on an LCD. I know "lcd.print(variable,2)" will print 2 decimals but is there a way to only print necessary decimals? For example if the variable:
1.00, then I want to print 1
1.20 then I want to print 1.2
1.22 then I want to print 1.22
I basically want the effect of "printf("%g",variable)" for LCDs.
Is it possible to do this? If yes, please let me know, thank you!

Edit:
If it is possible, it would be appreciated if you show me how.

2

I think I have seen this question before.

[edit]

Hmm, maybe not.

3

Of course it's possible. And easy, as well. Study the documentation for printing to the LCD or printing to anything. There is a second parameter you can supply that sets the decimal point to print. The default is two decimal places. For your program, the parameter is a zero.

4

Yes, it's possible to do this.

5

If i put 0 as the parameter then it won't print decimals at all. What are you talking about?

6

I mean test the float you are printing for the range of values that would give you a zero as the first decimal and print it with a zero parameter. If greater than that, test for the next range that will give you a single digit decimal and print with a 1 parameter, and continue with other ranges and parameters.

7

Yes. I have printed float values in LCD couple of times. You can see this simple example https://www.digikey.com/en/maker/projects/how-to-make-a-simple-digital-voltmeter-with-an-arduino/082dff9d725549aea8bf84a7e302c1b2
The voltage is printed here up to 2 digits after decimal.

8

may be this is a start:

void printFloat(Stream &s, float a)
{
  int i = (int)a;                  // the integer part
  float f = a - i;                 // the fraction
  int d100 = (int)(f * 100);       // 
  if (d100 == 0) s.print(a, 0);            // x.00
  else if (d100 % 10 == 0) s.print(a, 1);  // x.y0
  else s.print(a, 2);                      // x.yz
}


void setup() {
  Serial.begin(115200);
  float a = -12.345;
  printFloat(Serial, a);
  Serial.println();       // only for Serial, to jump to the next line
  a = -12.30;
  printFloat(Serial, a);
  Serial.println();
  a = -12.0;
  printFloat(Serial, a);

  //printFloat(lcd, a);    // should work if you have a lcd object
}

void loop() {
  // put your main code here, to run repeatedly:

}

will print:

-12.35
-12.3
-12

and you can hand over a lcd object instead of the Serial also.

9

Use dtostrf, then go to the end of the c-string and decrease position while the character is a '0', then put a '\0' on the next position, to mark the end of the c-string

10

Here is a modification (or overload) of dtostrf, with an additional parameter to trim the zeros, and does not break justification : t1055247.ino - Wokwi Arduino and ESP32 Simulator