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Read / write operation of trust file

2022-07-22 02:35:00 【51CTO】

List of articles

One 、 Read the file
Two 、 write file

One 、 Read the file

       
       use 
       
       std::fs::File;
       
       fn 
       
       main() {
       
       let 
       
       f 
       
       = 
       
       File::open(
       
       "hello.txt").
       
       unwrap();
       
}
      
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1、 Read in bytes

       
       use 
       
       std::fs::File;
       
       use 
       
       std::io::prelude::
       
       *;
       
       fn 
       
       main() {
       
       let 
       
       mut 
       
       f 
       
       = 
       
       File::open(
       
       "/src/1.txt").
       
       unwrap();
       
       let 
       
       mut 
       
       buf 
       
       = 
       
       vec
       
       ![
       
       0; 
       
       8];
       
       let 
       
       n 
       
       = 
       
       f.
       
       read(
       
       &
       
       mut 
       
       buf[..]).
       
       unwrap();
       
       println
       
       !(
       
       "{:?}", 
       
       &
       
       buf[..
       
       n]);
       
}
      
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2、 Read all

       
       use 
       
       std::fs::File;
       
       use 
       
       std::io::prelude::
       
       *;
       
       fn 
       
       main() {
       
       let 
       
       mut 
       
       f 
       
       = 
       
       File::open(
       
       "/src/1.txt").
       
       unwrap();
       
       let 
       
       mut 
       
       buf 
       
       = 
       
       String::new();
       
       f.
       
       read_to_string(
       
       &
       
       mut 
       
       buf).
       
       unwrap();
       
       println
       
       !(
       
       "{}", 
       
       buf);
       
}
      
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3、 Read line by line

       
       use 
       
       std::fs::File;
       
       use 
       
       std::io::prelude::
       
       *;
       
       use 
       
       std::io::BufReader;
       
       fn 
       
       main() {
       
       let 
       
       f 
       
       = 
       
       File::open(
       
       "/src/1.txt").
       
       unwrap();
       
       let 
       
       reader 
       
       = 
       
       BufReader::new(
       
       f);
       
       for 
       
       line 
       
       in 
       
       reader.
       
       lines() {
       
       // line  yes  std::result::Result<std::string::String, std::io::Error>  type 
       
       // line  Does not contain line breaks 
       
       let 
       
       line 
       
       = 
       
       line.
       
       unwrap();
       
       println
       
       !(
       
       "{}", 
       
       line);
       
    }
       
}
      
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Two 、 write file

       
       use 
       
       std::fs::File;
       
       use 
       
       std::io::prelude::
       
       *;
       
       fn 
       
       main() {
       
       let 
       
       mut 
       
       f 
       
       = 
       
       File::create(
       
       "/tmp/dst").
       
       unwrap();
       
       f.
       
       write(
       
       "Hello\n".
       
       as_bytes()).
       
       unwrap();
       
       f.
       
       write(
       
       "12233445556666\n".
       
       as_bytes()).
       
       unwrap()
       
}
      
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5、 Additional documents

       
       use 
       
       std::fs::OpenOptions;
       
       use 
       
       std::io::prelude::
       
       *;
       
       fn 
       
       main() {
       
       let 
       
       mut 
       
       f 
       
       = 
       
       OpenOptions::new().
       
       create(
       
       true).
       
       append(
       
       true).
       
       open(
       
       "/tmp/dst").
       
       unwrap();
       
       f.
       
       write(
       
       "Hello\n".
       
       as_bytes()).
       
       unwrap();
       
       f.
       
       write(
       
       "345667777\n".
       
       as_bytes()).
       
       unwrap();
       
}
      
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