Complete UpdateArea$()$ to output "areaPointer is null." if areaPointer is null. Otherwise, assign areaValue to the variable pointed to by areaPointer. End with a newline.

Ex: If the input is Y $9\mathrm{.}5,$ then the output is:

Area is $9\mathrm{.}5.$

$34567891011121314151617181920$

using namespace std;void UpdateArea$($double$*$ areaPointer, double areaValue$)\{$if $($areaPointer $=$ nullptr$)\{$ cout $<<$ areaValue $<<$"areaPointer." $<$