├── Cargo.lock
├── Cargo.toml
├── README.md
├── build.rs
├── num.c
├── num.h
├── src
│   ├── bindings.rs 
│   └── main.rs
└── wrapper.h

├── Cargo.toml

//  num.h
#ifndef NUM_H
#define NUM_H
 
void print_num(int num);
 
#endif
 
// num.c
#include <stdio.h>
#include "num.h"
 
void print_num(int num) {
    printf("num is mydemo from dalong %d",num);
}
wrapper.h
#include "num.h"
build.rs
use std::path::PathBuf;
fn main() {
 
    // build c library
 
    cc::Build::new()
    .file("num.c")
    .compile("num");
 
    // build rust bindings
 
    let bindings = bindgen::Builder::default()
        // The input header we would like to generate
        // bindings for.
        .header("wrapper.h")
        // Tell cargo to invalidate the built crate whenever any of the
        // included header files changed.
        .parse_callbacks(Box::new(bindgen::CargoCallbacks))
        // Finish the builder and generate the bindings.
        .generate()
        // Unwrap the Result and panic on failure.
        .expect("Unable to generate bindings");
 
    // Write the bindings to the $OUT_DIR/bindings.rs file.
    let out_path = PathBuf::from(".");
    bindings
        .write_to_file(out_path.join("src/bindings.rs"))
        .expect("Couldn't write bindings!");
}
main.rs
mod bindings;
use bindings::print_num;
 
fn main() {
 
    print!("call c ");
    unsafe {
        print_num(333);
    } 
}

#ifndef NUM_H

cargo build --release