extern C {//声明调用C语言的abs函数 fn abs(input:i32) - i32; } unsafe fn dangerous(){ println!(do something dangerous); } //不安全的trate unsafe trait Foo{ fn foo(self); } struct Bar(); unsafe impl Foo for Bar { fn foo(self){ println!(foo) } } fn foo() { let mut num 6; let r1 num as *const i32; let r2 mut num as *mut i32; unsafe { println!(r1 is {},*r1); println!(r2 is {},*r2); dangerous(); println!(abs(-3): {},abs(-3)); } } static mut COUNTER: u320; fn add_counter(inc: u32) { unsafe{ COUNTER inc; } } fn main() { let mut num5; //创建不可变和可变的裸指针只是不能在不安全的代码块只为解引用裸指针 let r1 num as *const i32; let r2 mut num as *mut i32; unsafe { println!(r1 is {},*r1); println!(r2 is {},*r2); dangerous(); } foo(); add_counter(3); add_counter(4); unsafe { println!(counter: {},COUNTER); } //不安全的trate let a Bar(); a.foo(); }