Embeding Rust in C hello world example

build_and_execute.sh

rustc --crate-type=staticlib hello.rs
g++ main.cpp -L. -lhello -o main
./main

hello.rs

// hello.rs
use std::ffi::CStr;
use std::os::raw::c_char;

#[no_mangle]
pub extern "C" fn hello_from_rust(name: *const c_char) {
    // Safety: We need to ensure that the input pointer is not null and points to valid C string data
    if !name.is_null() {
        // Convert the raw C string pointer to a safe Rust string slice
        let name_str = unsafe { CStr::from_ptr(name) };

        // Convert the Rust string slice to a UTF-8 string and print it
        if let Ok(name) = name_str.to_str() {
            println!("Hello, {}!", name);
        } else {
            eprintln!("Invalid UTF-8 sequence in input string");
        }
    } else {
        eprintln!("Null pointer passed as input");
    }
}

main.cpp

// main.cpp
#include <iostream>

extern "C" {
    void hello_from_rust(const char* str);
}

int main() {
    hello_from_rust("my friend");
    return 0;
}