join an array of substrings into a string in rust

To concatenate an array of substrings into a single string in Rust, you can use the join method provided by the Iterator trait. Here is an example:

main.rs
fn main() {
    let arr = ["foo", "bar", "baz"];
    let s = arr.join("");
    println!("{}", s); // Output: "foobarbaz"
}
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In this example, we first define an array arr containing three substrings. Then, we use the join method to concatenate the substrings with an empty separator string "". The resulting string s is printed to the console. Note that the join method returns a String, not a &str, so we can print it directly using {}.