Reading values from text file of unknown structure

[Beliavsky]

A thread about reading lines with unknown length was

Reading lines from a file without padding

I have long wondered how to read lines from a file in Fortran. The obvious character (len=1000) :: text ! connect file to unit iu read (iu,"(a)") text is often good enough but truncates lines that are longer than 1000 characters, and you don’t know if trailing blanks in text are actually in the file. Using a code by Jacob Williams to read a file into an allocatable string and then searching the string for newline characters, it is possible to recover the lines of a file. Here is the program r…