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34 lines
790 B
Rust
34 lines
790 B
Rust
//Import the `fmt` module.
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use std::fmt;
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//Define a structure named `List` containing a `Vec`.
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struct List(Vec<i32>);
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impl fmt::Display for List{
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result{
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//Extract the value using tuple indexing,
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//and create a reference to `vec`.
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let vec = &self.0;
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write!(f, "[")?;
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//Iterate over `v` in `vec` while enumerating the iteration count in `count`.
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for(count, v) in vec.iter().enumerate(){
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//For every element except the first, add a comma.
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//Use the ? operator, or try!, to return on errors.
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if count != 0{
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write!(f, ", ")?;
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}
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write!(f, "{}: {}", count, v)?;
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}
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//Close the opened bracket and return a fmt::Result value.
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write!(f, "]")
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}
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}
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fn main(){
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let v = List(vec![1, 2, 3]);
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println!("{}", v);
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}
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