("f64({})转i32({})",f,q);letmut num=[1,2,3];letmut y=num.as_mut_ptr();// 可变的指针类型letmut p=yasusize;// 把指针转为usize类型p+=4;// 指针步进一步(i32类型占4字节,因此加4即可)y=pas*mut i32;// 将 usize转为指针unsafe{println!("{}",*y);// 在unsafe模块中操作指针}...
Don't add only zeros to the numbers array (cce6a442) Add cast to usize, as it is confusing in the context of an exercise about Option (f6cffc7e) option2: Add TODO to comments (#400) (10967bce) options1: Add hint about Array Initialization (#389) (9f75554f) test2: name of type...
// true = 1,false = 0 println!("true = {},false = {}",good,not_good); let num = 6; println!("{}",num as bool); // error[E0054]: cannot cast `i32` as `bool` // Error[E0308]: mismatched types - expected `bool`, found `isize` if good { println!("You are so good...
{ slice::from_raw_parts(input_lon, lon_size as usize) }; let input_lat = unsafe { slice::from_raw_parts(input_lat, lat_size as usize) }; let combined: Vec<(i32, i32)> = input_lon .iter() .zip(input_lat.iter()) .map(|each| convert(*each.0, *each.1)) .collect(); ...
pubfnadd(left:usize,right:usize)->usize{left+right} 一切就绪后，我们现在可以将这个库编译为 ...
// Test clippy::cast_precision_loss @@ -457,3 +462,8 @@ fn issue11642() { //~^ ERROR: casting `i32` to `u32` may lose the sign of the value } } fn issue12506() -> usize { let bar: Result<Option, u32> = Ok(Some(10)); bar.unwrap().unwrap() as usize }190 changes...
std::mem::transmute::<&i32,usize>(ptr) };// Use an `as` cast insteadletptr_num_cast = ptras*consti32asusize; 将*mut T变成&mut T: letptr: *muti32= &mut0;letref_transmuted =unsafe{ std::mem::transmute::<*muti32, &muti32>(ptr) ...
#[no_mangle]pubextern"C"fnadd(a:i32, b:i32)->i32{ a + b } 上面的代码是Keyword extern中提到的将 Rust 函数导出到 C lib 中的标准做法,根据这篇帖子,extern和extern "C"实际上没有区别,因为 Rust 默认使用标准 C ABI 的格式导出。
unsafe fnfind_color(left:u32,top:u32,right:u32,bottom:u32,step:usize)->bool{leth_screen_dc=GetDC(null_mut());//获得屏幕的HDCletmem_dc=CreateCompatibleDC(h_screen_dc);//创建一个内存中的DCletmut rect:RECT=RECT{left:leftasi32,top:topasi32,right:rightasi32,bottom:bottomasi32,};//...
(WIDTH, size_of::<fn(i32) -> i32>()); const DOUBLE_WIDTH: usize = 2 * WIDTH; // 未定大小的结构体 struct Unsized { unsized_field: [i32], } // 指向未定大小类型的指针占用 2 个宽度 assert_eq!(DOUBLE_WIDTH, size_of::<&str>()); // 切片 assert_eq!(DOUBLE_WIDTH, size_of...