Question:
A user has asked us how to write data from a structure to a file using printf. without carriage returns being added to the middle of a record.

Answer:
If you run the following commands, it print the structure to a file with carriage returns:

IDL> A = {star, name:'Hello There!', ra:2.0, dec:3.0, inten:FLTARR(12)+4.0}
IDL> openw, 1, "test_struct_output.txt"
IDL> printf, 1, A
IDL> free_lun, 1

On way to workaround this issue is to use the FORMAT keyword to specify that all the elements within a structure are written to the same line. For example:

IDL> A = {star, name:'Hello There!', ra:2.0, dec:3.0, inten:FLTARR(12)+4.0}
IDL> printf, 1, A, FORMAT='(50A)'
IDL> free_lun, 1

Where the in the "(50A)' format, the '50' should be any number that is greater than the number of elements in the structure

David S.
-HGS.