FFI Structs

Foreign Function Interface types

CString

use std::ffi::CString;

fn main() {
    // CString - owned C string (null-terminated)
    let c_string = CString::new("Hello, C!").expect("CString::new failed");

    println!("=== CString ===");
    println!("as_ptr(): {:?}", c_string.as_ptr());
    println!("as_bytes(): {:?}", c_string.as_bytes());
    println!("as_bytes_with_nul(): {:?}", c_string.as_bytes_with_nul());

    // To/from Rust string
    let rust_str = c_string.to_str().expect("Invalid UTF-8");
    println!("to_str(): {}", rust_str);

    // Into raw pointer (for passing to C)
    let ptr = c_string.into_raw();
    println!("\ninto_raw(): {:?}", ptr);

    // Reclaim ownership
    let c_string = unsafe { CString::from_raw(ptr) };
    println!("Reclaimed: {:?}", c_string.to_str());

    // Error case: interior null
    let result = CString::new("Hello\0World");
    println!("\n=== Interior Null ===");
    println!("CString::new with \\0: {:?}", result);

    // Vec to CString
    let bytes = vec![72, 101, 108, 108, 111];  // "Hello"
    let c_string = CString::new(bytes).unwrap();
    println!("\nFrom Vec: {:?}", c_string.to_str());
}