cc67e4840f
git-subtree-dir: libs/CommService git-subtree-split: 7ccc0fce88bbc5969df060058cf0fb57abe3bcf9
40 lines
1.5 KiB
Markdown
40 lines
1.5 KiB
Markdown
# The Basics
|
|
|
|
The simplest CLI11 program looks like this:
|
|
|
|
[include](../code/simplest.cpp)
|
|
|
|
The first line includes the library; this explicitly uses the single file
|
|
edition (see [Selecting an edition](/chapters/installation)).
|
|
|
|
After entering the main function, you'll see that a `CLI::App` object is
|
|
created. This is the basis for all interactions with the library. You could
|
|
optionally provide a description for your app here.
|
|
|
|
A normal CLI11 application would define some flags and options next. This is a
|
|
simplest possible example, so we'll go on.
|
|
|
|
The macro `CLI11_PARSE` just runs five simple lines. This internally runs
|
|
`app.parse(argc, argv)`, which takes the command line info from C++ and parses
|
|
it. If there is an error, it throws a `ParseError`; if you catch it, you can use
|
|
`app.exit` with the error as an argument to print a nice message and produce the
|
|
correct return code for your application.
|
|
|
|
If you just use `app.parse` directly, your application will still work, but the
|
|
stack will not be correctly unwound since you have an uncaught exception, and
|
|
the command line output will be cluttered, especially for help.
|
|
|
|
For this (and most of the examples in this book) we will assume that we have the
|
|
`CLI11.hpp` file in the current directory and that we are creating an output
|
|
executable `a.out` on a macOS or Linux system. The commands to compile and test
|
|
this example would be:
|
|
|
|
```term
|
|
gitbook:examples $ g++ -std=c++11 simplest.cpp
|
|
gitbook:examples $ ./a.out -h
|
|
Usage: ./a.out [OPTIONS]
|
|
|
|
Options:
|
|
-h,--help Print this help message and exit
|
|
```
|