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Richard Nusser edited this page Jan 8, 2018 · 1 revision

If you're booting from an .iso image long file names get trimmed and this application might be called "hellowor" instead.

Features

Shows a variant of the traditional first program's output.

This application accepts command-line parameters:

FS0:\> helloworld -help
Greetings, non-spherical habitation rock!

[general options trimmed]

Group 1:
  -bool            boolean parameter
  -dbl <decimal>   double parameter [default: 0.66]

Group 2:
  -int <integer>  integer parameter [default: 2]

The output includes the effective values for these parameters: if they aren't supplied in the command line their defaults are used, for example passing a value to the -dbl parameter overrides the parameter's default value:

FS0:\> helloworld -dbl 12412
Greetings, non-spherical habitation rock!

There's a  -help  parameter that'll show command line options!

effective argument values after defaults:
  -bool: 0
  -dbl:  12412.00
  -int:  2

Technical Details

The "helloworld" application shows how to use command-line arguments: each argument is an array entry with type, optional validator, name and description. An array of command-line arguments gets wrapped in a group, the group gets an optional name and groups are passed to init().

The -help and logging parameters are built-in, each application automatically includes them.

Sources are in apps/helloworld.c.

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