NAG Library Function Document

nag_example_file_io (x04aec)

1  Purpose

2  Specification

3  Description

4  References

5  Arguments

1:     argc – intInput

On entry: the number of command-line arguments.

2:     argv[argc] – const char *Input

On entry: the argument vector.

3:     flag – const char *Input

On entry: indicates which file pointer or file name will be returned by the function. nag_example_file_io (x04aec) searches the command-line arguments contained in argv for flag. If it is found, in say $\mathbf{argv}\left[i-1\right]$, the function examines $\mathbf{argv}\left[i\right]$ and if it is a filename the function returns either a file pointer or the filename as follows:

$\mathbf{flag}=\text{"-data"}$

If $\mathbf{argv}\left[i\right]$ is a filename it specifies the data file to be opened for reading and a FILE pointer to that file is returned. Otherwise a FILE pointer to stdin is returned.

$\mathbf{flag}=\text{"-results"}$

If $\mathbf{argv}\left[i\right]$ is a filename it specifies the results file to be opened for writing and a FILE pointer to that file is returned. Otherwise a FILE pointer to stdout is returned.

$\mathbf{flag}=\text{"-options"}$

If $\mathbf{argv}\left[i\right]$ is a filename it specifies a file containing optional arguments to be opened for reading and this filename is returned in fname. Otherwise a default filename comprising the stem of the program name with a file extension of .opt (e.g., e04ucce.opt) is returned in fname. Note that memory is allocated internally to fname using NAG_ALLOC. It can be freed using NAG_FREE.

$\mathbf{flag}=\text{"-nag\_write"}$

If $\mathbf{argv}\left[i\right]$ is a filename it specifies a file to be opened for library output and this filename is returned in fname. Otherwise a NULL is returned in fname.

$\mathbf{flag}=\text{"-nag\_read"}$

If $\mathbf{argv}\left[i\right]$ is a filename it specifies a file to be opened for reading library input and this filename is returned in fname. Otherwise a NULL is returned in fname.

Constraint: $\mathbf{flag}=$ "-data", "-results", "-options", "-nag_write" or "-nag_read".

4:     fname – char **Input

On exit: if the flag specified is "-options", "-nag_write" or "-nag_read", fname contains the name of the file for reading or writing.

6  Error Indicators and Warnings

7  Accuracy

8  Parallelism and Performance

9  Further Comments

10  Example

10.1  Program Text

Program Text (x04aece.c)

10.2  Program Data

10.3  Program Results

Program Results (x04aece.r)