X04 Chapter Contents
X04 Chapter Introduction
NAG Library Manual

# NAG Library Routine DocumentX04BBF

Note:  before using this routine, please read the Users' Note for your implementation to check the interpretation of bold italicised terms and other implementation-dependent details.

## 1  Purpose

X04BBF reads a single formatted record from an external file.

## 2  Specification

 SUBROUTINE X04BBF ( NIN, RECIN, IFAIL)
 INTEGER NIN, IFAIL CHARACTER(*) RECIN

## 3  Description

X04BBF is used by NAG Library routines to read formatted records from an external file. All formatted input from an external file by NAG Library routines is performed by calls to X04BBF.

None.

## 5  Parameters

1:     NIN – INTEGERInput
On entry: the Fortran unit number which identifies the file to be read from. If ${\mathbf{NIN}}<0$ (not a valid Fortran unit number), then no input occurs.
2:     RECIN – CHARACTER(*)Output
On exit: the first LEN(RECIN) characters of the record read from unit NIN, padded with trailing blanks if the record was shorter than LEN(RECIN).
3:     IFAIL – INTEGERInput/Output
On entry: IFAIL must be set to $0$, $-1\text{​ or ​}1$. If you are unfamiliar with this parameter you should refer to Section 3.3 in the Essential Introduction 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 parameter, 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).

## 6  Error Indicators and Warnings

If on entry ${\mathbf{IFAIL}}={\mathbf{0}}$ or $-{\mathbf{1}}$, explanatory error messages are output on the current error message unit (as defined by X04AAF).
Errors or warnings detected by the routine:
${\mathbf{IFAIL}}=1$
An end-of-file was detected by the READ statement.
System-dependent errors may also occur if the unit specified by NIN is not connected to an external file, or if a read error occurs.

Not applicable.

None.

## 9  Example

This example program simply illustrates how a formatted record is read from the NAG Library, by first reading it into the character-string RECIN, used as an internal file, by X04BBF and then reading the internal file.

### 9.1  Program Text

Program Text (x04bbfe.f90)

### 9.2  Program Data

Program Data (x04bbfe.d)

### 9.3  Program Results

Program Results (x04bbfe.r)