Gfortran, finding empty text lines?

[solarblast]

Win 7 MinGW compilers.

I have a txt file that has empty lines that I'd like to pass by when reading them. Each line is assumed to be 85 characters. Here's a snippet of code:
Open(unit=astro_in, file="METEOR_LegacyInputToNML.txt", status = "OLD")

do while(.True.)
Read(unit=astro_in, fmt="(a85)", iostat=eof) card ! Read file card)
if ( (card(1:5) == 'GROUP') ) then
Write(*,*) "crd:",card
else if (card(1:3) == 'EOD') then
exit
else if (len(card) == 0) then
Write(*,*) "Blank", card
end if
len(card) is always 85 even if I have a line devoid of characters. len(card) is always seeing 85. How do I determine if a line is blank? Here's a few lines of the file.

GROUP Station #01 CARDS 02 fmt 501
# Station data
# ---R---|---PHIP--|---PHI---|--RLONG--|---TP----|-BN|--FL--|-STAHGT-|--COBS-|
# f10.4 f10.8 f10.8 f10.8 f10.7 f4.0 f7.3 f9.4 a8
6364.1543 .95003538 .953223371.97825229 .100000 6.203.200 00.6480MEANOK A
6364.2581 .94493380 .948132841.97141644 .100000 6.203.200 00.6721NEWBROOK B

GROUP MetTime #02 CARDS 01 fmt 502
# Time of meteor obs, no. obs per station, ... for each station
#H|MM|--SS--|----XJDM----|-NM|-NM|-NS|-NS|METNO|not input
# 2f3.0 F7.3 F13.5 I4 I4 I4 I4 A6 A6
2 12 13.0002435400.82885 40 39 1045MEANOK R2-1

GROUP SolarHz #03 CARDS 06 fmt 503

Maybe the file needs to be DAT??

 

[bigfooted]

If the length is 85, it is not devoid of characters but contains 85 spaces. So this will probably suffice:
else if (card(1:10) == ' ')

 

[AlephZero]

In Fortran 90 or later, you can use the len_trim(card) to find the length without any trailing blanks.

In earler versions of fortran, just compare card with a blank striing ' '. If you compare two strings of different lengths, the shorter one is padded with blanks .

Some versions of fortran had a non-standard format descriptor Q which returned the actual number of characters read from the file, i.e.

read(astro_unit, 500) nc, card
500 format(q,a)

This was just about the only way in Fortran to find out if a line in a data file actually contains trailing blank characters - but a file format where trailing blanks are "significant" is probably a bad idea for reasons that have nothing to do with Fortran! More usefully, the Q format also tells you if the line was longer than the variable "card" and some data was truncated.

 

[solarblast]

Ah, I've been wondering about trim and the others. I finally just put EOD at the start of the first line.