How to read number of lines in Fortran 90 from a text file?

Question

How to read number of lines present in a text file.

My text file seems to be like:

1
2
3
.
.
.
n

Answer 1

nlines = 0 
OPEN (1, file = 'file.txt') 
DO 
    READ (1,*, END=10) 
    nlines = nlines + 1 
END DO 
10 CLOSE (1) 

print*, nlines

end

P.S. I totally disagree that this question "seems unclear and shows no effort". Man, you just don't know what you're saying. This question is firstly absolutely clear and secondly it does not have to "show any effort" - that's a stupid requirement in this case, because it is a common practice to ask "how to do A in a language B" - with no efforts required.

OR:

nlines = 0 
OPEN (1, file = 'file.txt')
DO
  READ(1,*,iostat=io)
  IF (io/=0) EXIT
  nlines = nlines + 1
END DO
CLOSE (1)

print*, nlines

Answer 2

Although unclear, but i think, if you just have to know the number lines in the files, just use wc -l <filename> in the command line

if you want to do anything further, just read the number of lines a character string and count until the end of file is encountered. here is the code below

character :: inputline*200

OPEN(lin, file=inputfile, status='old', action='read', position='rewind')

loop1: DO
READ(lin,*,iostat=eastat) inputline
IF (eastat < 0) THEN
    numvalues = numvalues + 1
WRITE(*,*) trim(inputfile), ' :number of records =', numvalues-1
EXIT loop1

ELSE IF (eastat > 0) THEN
    STOP 'IO-error'
ENDIF
    numvalues = numvalues + 1 

END DO loop1

hope that helps!