Getting the number of decimal places: Difference between revisions

=={{header|jq}}==

The current (March 2023) official releases of jq, gojq, fq, and jaq cannot be relied upon

to preserve the literal form of numbers, and in particular they drop the

final 0 of `12.3450` when presented as a number. However, the current "master" version of jq retains

the literal form of numbers. Accordingly, both the numeric and the string forms of 12.3450 are included in the suite of test

cases, and two sets of results are presented below.

<syntaxhighlight lang=jq>

def number_decimal_digits:

. as $in

| def nil: . == null or . == "";

def nodecimal: # e.g. 12 or 12e-2

capture("^[-+]?[0-9]*([eE](?<sign>[-+]?)(?<p>[0-9]+))?$")

| if .sign|nil then 0

elif .p|nil then "internal error: \($in)"|error

else .p|tonumber

end;

tostring

| nodecimal

// capture("^[-+]?[0-9]*[.](?<d>[0-9]+)([eE](?<sign>[-+]?)(?<p>[0-9]+))?$") # has decimal

// null

| if type == "number" then .

elif not then 0

elif .d|nil then 0

elif (.sign|nil) and .p == null then .d|length

elif (.sign|nil) or .sign == "+" then [0, (.d|length) - (.p|tonumber)] | max

elif .sign == "-" then (.d|length) + (.p|tonumber)

else "internal error: \($in)"|error

end ;

def examples:

[12.345, 3],

[12.3450, 4],

["12.3450", 4],

[1e-2, 2],

[1.23e2, 0];

def task:

examples

| (first|number_decimal_digits) as $d

| if $d == last then empty

else "\(first) has \(last) decimal places but the computed value is \($d)"

end;

task, "Bye."

</syntaxhighlight>

{{output}}

Using gojq:

<pre>

12.345 has 4 decimal places but the computed value is 3

Bye.

</pre>

Using jq post-1.6:

<pre>

Bye.

</pre>