1.2 rust cargo

cargo是rust的编译与打包工具，可将rust打包成为一个可执行性文件。生成的可执行性文件不能跨系统的大版本，比如在linux7上打包，那么程序无法在linux6上执行。

# cargo new hello_cargo
Created binary (application) `hello_cargo` package
# cd hello_cargo
# ls
Cargo.toml src

# ll -a
total 24
drwxr-xr-x 4 root root 4096 Jan 15 18:16 .
drwxr-xr-x 3 root root 4096 Jan 15 18:16 ..
-rw-r--r-- 1 root root  121 Jan 15 18:16 Cargo.toml
drwxr-xr-x 6 root root 4096 Jan 15 18:16 .git
-rw-r--r-- 1 root root   19 Jan 15 18:16 .gitignore
drwxr-xr-x 2 root root 4096 Jan 15 18:16 src

# cat Cargo.toml 
[package]
name = "hello_cargo"
version = "0.1.0"
authors = ["tanpf <itoracle@163.com>"]
edition = "2018"

[dependencies]

# cd src
# ls
main.rs
# cat main.rs 
fn main() {
    println!("Hello, world!");
}

[root@itoracle src]# cargo build
   Compiling hello_cargo v0.1.0 (/usr/local/automng/src/rust/test/hello_cargo)                                                                                              
    Finished dev [unoptimized + debuginfo] target(s) in 3.05s                                                                                                               
[root@itoracle src]# ll
total 4
-rw-r--r-- 1 root root 45 Jan 15 18:16 main.rs

[root@itoracle hello_cargo]# ./target/debug/hello_cargo 
Hello, world!

[root@itoracle hello_cargo]# cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s                                                                                                               
     Running `target/debug/hello_cargo`
Hello, world!
[root@itoracle hello_cargo]# 
[root@itoracle hello_cargo]# 
[root@itoracle hello_cargo]# vim src/main.rs 

fn main() {
    println!("Hello, world!");
    println!("过年回家的火车票，为啥每次都抢不到呢");
}

如果修改了代码，cargo run会先编译再运行

[root@itoracle hello_cargo]# cargo run
   Compiling hello_cargo v0.1.0 (/usr/local/automng/src/rust/test/hello_cargo)                                                                                              
    Finished dev [unoptimized + debuginfo] target(s) in 0.46s                                                                                                               
     Running `target/debug/hello_cargo`
Hello, world!
过年回家的火车票，为啥每次都抢不到呢

cargo check进行代码的编译，但不生成可执行文件，速度比cargo build快很多，当代码比较多时，可以先check

[root@itoracle hello_cargo]# cargo check
    Checking hello_cargo v0.1.0 (/usr/local/automng/src/rust/test/hello_cargo)                                                                                              
    Finished dev [unoptimized + debuginfo] target(s) in 0.13s