How to set double precision in arduino without c/c++ libraries

Using Arduino Programming Questions
1

I just want to know how i can adjust double precision/ the number of digits, currently i have two digits but i want to have only one, i did a bit of research and found out it's pretty easy in c++ with the library but unfortunately they are not supported by atmel, so i just want to know how can i adjust the precision without the library?
Possibly with a string and format specifiers?

2

look up sprintf modifiers

3

AVR based Arduinos do single precision floating point (6-7 digits total accuracy), even if you specify double , but those with other types of microprocessors support double precision (about 15 digits).

Serial.print(value, n): n specifies number of digits past the decimal point (default 2).

4

That's the number of digits to print, which is different that the number of digits that are "valid" in the value... (in case that wasn't clear to OP.)

5

Yeah i need to change number of digits in variable because i'll print that value to a display.

6

If display print method does not have overload where you can specify number of decimals, then use sprintf to format it

7

Thanks i will try it.

8

sprintf does not support floats on many arduinos.

9

Are you asking about Serial.print()? As in:

Serial.print(1.23456, 0) gives "1"
Serial.print(1.23456, 2) gives "1.23"
Serial.print(1.23456, 4) gives "1.2345"
10

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