>in report designer
>can we define a function or do prg file in format column ?

If you just want some code to run for a report field, you can put a function call in the PrintWhen expression - but keep in mind that it may run more times than you think, and that may slow down your report.

If you need a variable format for your column, I'm not sure - last time I had macro expansion there, it was in FPD days. You can use transform(myField, MyFormattingFunction()) as a field expression - but again, it may be calculated more times than you'd expect, and may slow down your report.