The EOF function tests the specified file unit for the end-of-file condition.
Note: The EOF function cannot be used with files opened with the RAWIO keyword to the OPEN routines. Many of the devices commonly used with RAWIO signal their end-of-file by returning a zero transfer count to the I/O operation that encounters the end-of-file.
If file unit number 1 is open, the end-of-file condition can be checked by examining the value of the expression EOF(1). For example, the following IDL code reads and prints a text file:
; Open the file readme.txt:
OPENR, 1, 'readme.txt'
; Define a string variable:
A = ''
; Loop until EOF is found:
; Read a line of text:
READF, 1, A
; Print the line:
; Close the file:
Result = EOF(Unit)
If the file pointer is positioned at the end of the file, EOF returns true (1), otherwise false (0) is returned.
The file unit to test for end-of-file.