Fortran Programming
CSCE 150 Lab 7
File Processing
1. File Processing
2. Sample Program
3. Exercise for Credit
1. File Processing
Sometimes it is convenient in a Fortran program to use files for accessing or storing data,
especially when large amounts of data are involved. Too much keyboard input during the
run of a program leads to mistakes and tedium, while too much screen output has similar
consequences. Putting data into files - both for input and output - is a more leisurely and
less error-prone approach.
There are three steps for using files in a Fortran program:
1. Open a file for read or write. The file used for writing may be either new or a
replacement of an existing file.
2. Read or write data to the file.
3. Close the file.
Note: When you use a file for reading, you need to create this file if it does not exist.
Step 1: Open
Opening a file for input
Open (UNIT=unit_number, FILE=filename, STATUS='OLD', &
ACTION='READ', IOSTAT=ierror)
Opening a file for output
Open (UNIT=unit_number, FILE=filename, STATUS='NEW ', &
ACTION='WRITE', IOSTAT=ierror)
Open (UNIT=unix_number, FILE=filename, STATUS='REPLACE', &
ACTION='WRITE', IOSTAT=ierror)
unit_number is and integer used to uniquely identify the file.
filename is the name (including the path) of the file.
STATUS specifies the status of the file:
oOLD: file already exists (used for file reading).
oNEW: file does not exist (used for creating a new file without
overwriting any file with the same name)
oREPLACE: Used for creating a new file. If another file with the
same name exist, then overwrite the existing file.
ACTION specifies the purpose of file opening (reading or writing).
