Get length of a fully represented float

General Usage
13

Try also code below using significant digits and based on this other post.

using Printf

function full_float_signif(x::Float64, sigdig::Int)
    (x == 0) && (return (1, "0"))
    x = round(x, sigdigits=sigdig)
    n = length(@sprintf("%d", abs(x)))              # length of the integer part
    if (x ≤ -1 || x ≥ 1)
        decimals = max(sigdig - n, 0)               # 'sig - n' decimals needed 
    else
        Nzeros = ceil(Int, -log10(abs(x))) - 1      # No. zeros after decimal point before first number
        decimals = sigdig + Nzeros
    end
    s = @sprintf("%.*f", decimals, x)
    return length(s), s
end

# Example:
full_float_signif(1.87589e-17, 6)    # (24, "0.0000000000000000187589")