Variable floating-point precision format string

Question

I'm trying to print floating point numbers as percentages, and I'd like for the number of digits after the decimal place to vary as needed. Currently I have:

fmt.Printf("%.2f%%\n", 100*(value/total))

The problem is that if my percentage is, say, exactly 50, I will get the following output:

50.00%

While what I want is to get:

50%

Is there any way for the format string to indicate that a maximum of 2 digits of precision should be used, but only if needed?

Answer 1

There's no direct solution with the fmt package.

But you can remove the dot and zeros at end with a regular expression:

r, _ := regexp.Compile(`\.?0*$`)
fmt.Printf("%s%%\n", r.ReplaceAllString(fmt.Sprintf("%.2f", 100*(value/total)),""))

Bonus: the same regex works for any number of trailing zeros.

Side note: You'll display 50.0041 the same way than 50, which might be a little misleading.