# NAG Library Routine Document

## 1Purpose

x04adf closes a file associated with a given Fortran unit number.

## 2Specification

Fortran Interface
 Integer, Intent (In) :: iounit Integer, Intent (Inout) :: ifail
#include nagmk26.h
 void x04adf_ (const Integer *iounit, Integer *ifail)

## 3Description

x04adf is especially useful if the calling language is not Fortran. It closes a file associated with a given Fortran unit number.

None.

## 5Arguments

1:     $\mathbf{iounit}$ – IntegerInput
On entry: the Fortran unit number which identifies the file to be closed.
2:     $\mathbf{ifail}$ – IntegerInput/Output
On entry: ifail must be set to $0$, $-1\text{​ or ​}1$. If you are unfamiliar with this argument you should refer to Section 3.4 in How to Use the NAG Library and its Documentation for details.
For environments where it might be inappropriate to halt program execution when an error is detected, the value $-1\text{​ or ​}1$ is recommended. If the output of error messages is undesirable, then the value $1$ is recommended. Otherwise, if you are not familiar with this argument, the recommended value is $0$. When the value $-\mathbf{1}\text{​ or ​}\mathbf{1}$ is used it is essential to test the value of ifail on exit.
On exit: ${\mathbf{ifail}}={\mathbf{0}}$ unless the routine detects an error or a warning has been flagged (see Section 6).

## 6Error Indicators and Warnings

If on entry ${\mathbf{ifail}}=0$ or $-1$, explanatory error messages are output on the current error message unit (as defined by x04aaf).
Errors or warnings detected by the routine:
${\mathbf{ifail}}=1$
Failure to close the file.
${\mathbf{ifail}}=-99$
See Section 3.9 in How to Use the NAG Library and its Documentation for further information.
${\mathbf{ifail}}=-399$
Your licence key may have expired or may not have been installed correctly.
See Section 3.8 in How to Use the NAG Library and its Documentation for further information.
${\mathbf{ifail}}=-999$
Dynamic memory allocation failed.
See Section 3.7 in How to Use the NAG Library and its Documentation for further information.

Not applicable.

None.

## 10Example

This example program simply illustrates how to close a file once it has been opened for writing followed by how to close a file once it has been opened for reading.