# Getting fortran to read a text file and write the whole file to a different location

1. Feb 6, 2012

### charlie87

The issue I am having is that I want to create a program which reads a .txt file and copies it exactly to a .inp file followed by some coordinates which I am generating. the . txt file is being used as a header file which can be changed outside the program but once the program is read in the new variables are automatically updated.

Below is the text which I want to read. is there a command for read all?

$title simple wing$datacheck
0.
$symmetry - xz plane of symmetry =misymm mjsymm 1. 0.$mach number
=amach
.6
$cases - no. of solutions =nacase 1.$angles-of-attack
=alpc
4.
=alpha(1) alpha(2) alpha(3)
0. 10. 0.
$printout options =isings igeomp isingp icontp ibconp iedgep 4. 0. 0. 1. 1. 0. =ipraic nexdgn ioutpr ifmcpr .0 .0 1. 0. 3.$references for accumulated forces and moments
=xref yref zref nref
46. 0. 0.
=sref bref cref dref
2400. 60. 40. 90.
\$points - wing-body with composite panels
=kn cpnorm
1. 2.
=kt
1.
=nm nn netname

I than want this text to be written to a new file "pan.inp" in the same format.

Regards,
Charles Pearce

File size:
901 bytes
Views:
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2. Feb 6, 2012

### AlephZero

Re: Getting fortran to read a text file and write the whole file to a different locat

It's messy to make a completely general solution to this in Fortran. The way I would probably do that would be to write a 5-line C function that did the copying and call it from the Fortran program.

But judging from your sample data, you don't need a completely general solution, because you only have printable text and the lines of the file are reasonably short. So...

* Declare a character string longer than the longest line of text (e.g. 1000 characters should be plenty)
* Start an "infinite" loop.
* Read a line from the file using A format. This will pad out the line with blank characters.
Use the "END=" option to break out of the loop at the end of the file.
* Find where the last non-blank character is.
* Write the correct length substring to the output file, again using A format.
* End of loop.

3. Feb 7, 2012

### charlie87

Re: Getting fortran to read a text file and write the whole file to a different locat

thanks AlephZero,

however this route will not work for me as I need the exact number of spaces between each word or number. the formatting for this would be too time consuming so i will create a batch file in C which copies instead.

regards,
Charles

4. Feb 7, 2012

### Staff: Mentor

Re: Getting fortran to read a text file and write the whole file to a different locat

AlephZero's method does preserve all the spaces between numbers or words on each line. It's just that the read operation adds spaces to the end of each line in order to fill out the fixed-size character array that you're reading into. His method ignores those extra spaces at the end of the array when writing it to the other file, by writing only up to the last non-blank character.

If your data does have spaces at the ends of lines, and those spaces are significant, then AlephZero's method will not work for you.

5. Feb 7, 2012

### AlephZero

Re: Getting fortran to read a text file and write the whole file to a different locat

Some compilers for older versions of fortran used to have a non-standard Q format, which returned the exact number of characters on a line including trailing spaces, but that isn't available in gcc fortran, for example.

On the other hand gcc fortran does have intrinsic functions FGetC and FPutC which will do I/O one character at a time, not one record (line) at a time.