**Clap** is a simple-to-use, efficient, and full-featured library for parsing command line arguments and subcommands when writing console/terminal applications.
Here is an example of a simple program:
```rust
use clap::Clap;
/// Simple program to greet a person
#[derive(Clap, Debug)]
#[clap(name = "hello")]
struct Hello {
/// Name of the person to greet
#[clap(short, long)]
name: String,
/// Number of times to greet
#[clap(short, long, default_value = "1")]
count: u8,
}
fn main() {
let hello = Hello::parse();
for _ in 0..hello.count {
println!("Hello {}!", hello.name)
}
}
```
The above example program can be run as shown below:
```
$ hello --name John --count 3
Hello John!
Hello John!
Hello John!
```
The program also has automatically generated help message:
```
hello
Simple program to greet a person
USAGE:
hello [OPTIONS] --name <name>
FLAGS:
-h, --help Prints help information
-V, --version Prints version information
OPTIONS:
-c, --count <count> Number of times to greet [default: 1]
