How to read files while running fortran program?

In summary, the User's Manual for a Fortran simulation states that to run the simulation, one needs to read several input files. The program needs to open and read from these files, which can be done by specifying their names in the command line when running the program. The process of specifying the file names can vary depending on the program's source code.
  • #1
ngendler
20
0
Hi,

I am trying to run a simulation written mostly in Fortran on Linux. The User's Manual says that "To run a simulation one needs to read several input files." Then, it lists a bunch of files. I was wondering what it means by that and how I "read" the files?

Thanks in advance,

Naomi
 
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  • #3
@jtbell, thank you but no. I'm not trying read files within the program. The program is all completely written. But now when I run it, I think I need to link to those files or something, I'm not sure.
 
  • #4
ngendler said:
@jtbell, thank you but no. I'm not trying read files within the program. The program is all completely written. But now when I run it, I think I need to link to those files or something, I'm not sure.
"Link" has a very specific meaning in compiled programming languages such as Fortran, and is not applicable in your case. Your program needs to open the files and read from them, as described in the link that jtbell provided.

Your program needs to know the names of the files that it will be getting input from. The names of these files could be hardcoded in strings in the program, taken as input at run time, or passed on the command line when the program begins running. Without seeing the source code of your program, we can't say what you need to do to run it.
 
  • #5
Nevermind, I figured it out. I just included the file as < file.txt > in the command line where I ran the program.
 

Related to How to read files while running fortran program?

1. How do I read a file while running a Fortran program?

To read a file while running a Fortran program, you will need to use the OPEN and READ statements. The OPEN statement is used to open the file and specify the file name and access mode. The READ statement is used to read the contents of the file into variables or arrays in your program.

2. What is the syntax for the OPEN statement in Fortran?

The syntax for the OPEN statement in Fortran is:

OPEN(unit, file, status, [access,] [form,] [recl,] [blank,] [position,] [action,] [delim,] [pad,] [err,] [iostat,] [iomsg])

Where unit is the logical unit number, file is the name of the file, status specifies whether the file is being opened for reading, writing, or both, and the other parameters are optional.

3. How do I specify the access mode for a file in the OPEN statement?

You can specify the access mode for a file in the OPEN statement by using the access parameter. This parameter can take on the values 'SEQUENTIAL' or 'DIRECT', depending on whether you want to read the file sequentially or access specific records directly.

4. What is the difference between sequential and direct access in Fortran?

Sequential access means that the program will read the file in the order that the data is stored, from beginning to end. Direct access, on the other hand, allows the program to access specific records in the file without having to read through all the previous records. This can be more efficient for large files.

5. How do I handle errors while reading a file in a Fortran program?

You can handle errors while reading a file in a Fortran program by using the err or iostat parameters in the OPEN statement. These parameters will return an error code if there is a problem with opening or reading the file. You can then use the iostat or iomsg functions to retrieve the specific error message and handle it accordingly in your program.

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