如何從陣列

Question

我到一個數組序列兩個值，我試圖去通過WriteBuf但我得到的錯誤是

error: the trait `std::io::Write` is not implemented for the type `[_; 12]` 
error: type `std::io::buffered::BufWriter<&mut [_; 12]>` does not implement any method in scope named `write_be_u32` 
error: type `std::io::buffered::BufWriter<&mut [_; 12]>` does not implement any method in scope named `write_be_f64` 

這裏是最少的代碼生成此錯誤打造WriteBuf ：

use std::io::{ BufWriter, Write }; 

fn main(){ 
    let packed_data = [0; 12]; 
    let timestamp : u32 = 100; 
    let value : f64 = 9.9; 

    let writer = BufWriter::new(&mut packed_data); 
    writer.write_be_u32(timestamp); 
    writer.write_be_f64(value); 

    println!("Packed data looks like {:?}", packed_data); 
} 

我沒有正確借用切片？我注意到使用適當的模塊來爲我的緩衝區定義Write特徵嗎？

下面是該代碼的圍欄：http://is.gd/ol8qND

Answer 1

我看到你的代碼的一些潛在的問題：

• packed_data不可變。
• 您在main的末尾使用packed_data，而writer保留對其的可變引用。

我不認爲這些事情都是導致錯誤。然而，我確實發現一些作品：

use std::io::{ BufWriter, Write }; 

fn main() { 
    let mut packed_data = [0; 12]; 

    { 
     let packed_data_ref: &mut [u8] = &mut packed_data; 
     let mut writer = BufWriter::new(packed_data_ref); 

     writer.write(&[1, 2, 3, 4]).unwrap(); 
    } // `writer` gets deallocated and releases the mutable reference 

    println!("Packed data looks like {:?}", packed_data); 
} 

[playpen]

所以我想的問題是，你需要一個&[u8]而非&[u8; 12]。我不知道爲什麼。我希望這至少有助於。