if I open a file with
str = OpenWrite[filename, FormatType->FortranForm];
then, for instance, Write[str,N[Pi^100]] has the expected behaviour (it yields 5.187848314319587e49), whereas WriteString[str, N[Pi^100]] does not (it writes the string in OutputForm to the file).
Is this a bug or a feature? I can't use Write because I have lots of strings and Write always prints quotes. My workaround is to use FortranForm within WriteString, but it is really annoying.