1-D FFT for BCB

Because I have to choose a set of the sample frequency and data points of one package
in my Master project, I must write the c++ code for FFT ~
I get this core of FFT algorithm from homework of image processing ~
It's a 2-D FFT algorithm that display frequency-domain information of input image,
I change it a little bit for my application ~
I write a function that inputs a 1-D real-number form array in time-domain
and outputs 1-D real real-number form array in frequency-domain~
this function includes other functions like as transfer a real-number array
to a complex-number array, its' inverse, FFT algorithm ...
When output array is gotten , it must be fixed range for display~