function IsNaN ( const Float : Single | Double | Extended ) : Boolean;
Description
The IsNaN function returns True if the Float parameter is Not a number.
A floating point number can be set to such a value when it is assigned an undetermined value. The standard is :
NAN = 0.0 / 0.0
Related commands
Infinity Floating point value of infinite size
IsInfinite Checks whether a floating point number is infinite
NaN Not a real number
Example code : Assign NAN to a number and then test using IsNaN
var
float : Double;
begin
// Set the number to an invalid number
float := NAN; // Equivalent to 0.0/0.0
// Although an invalid number, we can still display it
ShowMessage('float = '+FloatToStr(float));
// And we can test to see if it is a valid number
if IsNaN(float)
then ShowMessage('float is not a number')
else ShowMessage('float = '+FloatToStr(float));
end;
Show full unit code
float = NAN
float is not a number