discrete fourier transformer uses digital signals whereas the fast fourier transform uses both analog and digital.

They are similar. In many problems, both methods can be used. You can view Fourier transform is the Laplace transform on the circle, that is |z|=1. When you do Fourier transform, you don't need to worry about the convergence region. However, you need to find the convergence region for each Laplace transform.

The discrete version of Fourier transform is discrete Fourier transform, and the discrete version of Laplace transform is Z-transform.

Fourier series is the sum of sinusoids representing the given function which has to be analysed whereas discrete fourier transform is a function which we get when summation is done.

The fast fourier transform, which was invented by Tukey, significantly improves the speed of computation of discrete fourier transform.

i want c code for fourier transform?