In the previous section, Rust's development environment was installed . This section begins with the first program and the introduction Use of Cargo.
hello world
Create Hello manually_ World folder:
mkdir hello_world cd hello_world
Then create a hello_world.rs file, i.e. t rust source file:
touch hello_world.rs
Write the following code:
fn main() {
println!("hello world");
}
Rust is indented with 4 spaces instead of tab
println here! It's a macro, not a function, not a function!
Compile with rustc(Rust Compile) and run the executable:
$ rustc hello_world.rs $ ./hello_world hello world
Rust is an ahead of time (precompiled) language. You can compile the program first and give the executable file to others to run without installing rust.
rustc is used for small projects, and cargo is also used for large projects.
cargo
cargo is Rust's build system and package management tool. This includes building code, downloading dependent libraries, and building these libraries.
cargo will be installed by default after Rust installation. You can view it in the following ways:
$ cargo --version cargo 1.58.0 (f01b232bc 2022-01-19)
View help details:
$ cargo -h
Rust Package manager for
USAGE:
cargo [+toolchain] [OPTIONS] [SUBCOMMAND]
OPTIONS:
-V, --version Print version information and exit
--list Installation command list
--explain <CODE> function`rustc --explain CODE`
-v, --verbose Use detailed output(-vv Very detailed/build.rs output)
-q, --quiet Do not print cargo log information
--color <WHEN> to color: auto, always, never
--frozen requirement Cargo.lock and cache It's the latest
--locked requirement Cargo.lock It's the latest
--offline Run without accessing the network
--config <KEY=VALUE>... Override configuration value(instable)
-Z <FLAG>... Cargo Unstable options for(Only nightly)，see also`cargo -Z help`Learn more
-h, --help print the help information
Some common cargo commands are as follows. cargo --list view all commands.
build, b Compile the current package
check, c Analyze the current package and report errors, but do not build the object file
clean delete target catalogue
doc, d Documentation for building this package and its dependencies
new Create a new cargo package
init Create a new in an existing directory cargo package
run, r Binaries or examples of running local packages
test, t Run test
bench Run benchmark
update Update in Cargo.lock Dependencies listed in
search search crates registry
publish Package and upload this package to the registry
install install Rust Binary file. The default location is $HOME/.cargo/bin
uninstall uninstall Rust Binary file
For more information about specific commands, see cargo help < command >.
cargo create project
The cargo new project will be automatically initialized as a VCS repository. You can specify the version control system (git, hg, pijul, or fossil) through -- vcs vcs, or specify -- vcs none to indicate that no version control will be initialized. If not specified, it defaults to git or cargo new VCS configuration value.
Create a hello with cargo_ Cargo project folder:
$ cargo new hello_cargo
Created binary (application) `hello_cargo` package
Enter hello_cargo directory, view the structure:
$ tree
.
├── .gitignore
├── Cargo.toml
└── src
└── main.rs
src is the source file directory with main rs.
. gitignore description is a VCS project.
Cargo.toml is a package management file. TOML is Tom's obvious, minimal language format, which is the configuration format of cargo.
[package] name = "hello_cargo" version = "0.1.0" edition = "2021" # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html [dependencies]
[package] is the area title. The following content is used to configure the package:
- Name: project name
- Version: project version
- authors: Project author
- edition: Rust version used
[dependencies] at the beginning of another area, the dependencies of the project are listed below.
In Rust, the package (Library) of code is called crate
If the t rust plug-in is installed in vscode:
vscode open hello_ In the cargo project folder, you will see that the target directory is generated by automatic compilation. Normally, it will not be generated without executing the command:
tree
.
tree
.
├── Cargo.lock
├── Cargo.toml
├── src
│ └── main.rs
└── target
├── CACHEDIR.TAG
└── debug
├── build
├── deps
│ ├── ellipsis
├── examples
└── incremental
├── ellipsis
build compilation
cargo build generates the target/debug / {project name} executable.
It will also generate cargo in the root directory of the project Lock file is used to track the library version that the project depends on. It does not need to be modified manually.
cargo build --release optimizes the compilation, and the compilation time will be longer.
The executable file will be generated in: target/release / {project name}
Run run
cargo run is divided into two steps: compiling and running. After the first compilation, if the code has not changed, only run will be executed and will not be rebuilt.
cargo run --release optimizes the operation after compilation. The compilation time will be longer and the code will run more efficiently.
The executable file will be generated in: target/release / {project name}
Check check
Check the code to ensure that it compiles smoothly, but does not produce executable files.
What is the difference between check and build in cargo?
Check is much faster than build in speed. You can check repeatedly during coding, which greatly improves the efficiency.
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