Need help with formula

Hi, I need Some help. i have report which generate invoice, there is two amount field one in $ and other is PK , In $ field always some value but some time pk field is null,

Now

i need some formula which is check,when PK field is null then convert $ field in word else convert pk field

hope you are understand my question

I use blow formula to convrt number into word this formula working perfectly

currencyvar tt;
currencyvar dect;
tt :={ship.comm_amount};
dect := tt - Truncate(tt);
tt := truncate(tt);
dect := dect * 100;
if dect = 0 then
UPPERCASE('$ ' + ToWords (tt,0 )) + ' ONLY'
else
UPPERCASE('$ ' + ToWords (tt,0) + ' And CENT ' + ToWords(dect,0)) + ' ONLY ';


Thanks in advance

You may use the IsNull function to test the field and construct the If-Then-Else around your existing formula
Extracted from Crystal Reports help

Quote:

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IsNull (fld)
Basic and Crystal syntax.

Arguments
fld is any valid database, memo, or BLOB field.
Returns
Boolean Value

Action
Evaluates the field specified in the current record and returns TRUE if the field contains a null value.

Typical uses
You can use this function in a record selection formula to limit the report to records that have something other than a null value in the field specified. You can also use it to have the program take some action whenever it encounters a null value.

Comments
Some databases support null data values and others do not. This function will not work if the active database(s) do not support null values. If the database(s) do support null values, the function can be used to reference the null values that get created as the result of a failed lookup while joining.

Note: Zero and blank (empty or " ") are not null values.

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JG