Non-advancing read in Fortran with free format

Question

I want to read a line in a file, which includes three real numbers, without advancing the pointer. So I wrote: (TXT is the variable representing my file which has a value of 80)

read(TXT, *, ADVANCE='NO') (numbers(i),i=1,3)

However, I got an error message saying:

"error #6568: This use of the ADVANCE, SIZE, or EOR specifier is invalid."

So how should I write it to make it correct?

Thanks.

Transude

If the reason you don't want to advance to the next line is that there is more data to read on the line, a common approach is to read the whole line into a string using the "(a)" format and then repeatedly read from the string. – Bossuet

Answer 1

You can use advance='no' only with an explicit format. The reason is the following : advance='no' just avoids to go to the next record (notice that the file pointer advances anyway, just after the last read value); but with a directed list (format *), one doesn't know how many record are involved by your read statement (the three numbers may be written on four lines for instance).

Dugger

Also note that ADVANCE can only be used for reading from an external unit. I got burned trying to read from a character array. – Exult