Concatenate string literal with another string

Question

Is there some reason why I cannot concatenate a string literal with a string variable? The following code:

fn main() {
    let x = ~"abcd";
    io::println("Message: " + x);
}

gives this error:

test2.rs:3:16: 3:31 error: binary operation + cannot be applied to type `&'static str`
test2.rs:3     io::println("Message: " + x);
                           ^~~~~~~~~~~~~~~
error: aborting due to previous error

I guess this is a pretty basic and very common pattern, and usage of fmt! in such cases only brings unnecessary clutter.

score 7 · Answer 1 · edited Oct 09 '14 at 08:40

7

With the latest version of Rust (0.11), the tilde (~) operator is deprecated.

Here's an example of how to fix it with version 0.11:

let mut foo = "bar".to_string();
foo = foo + "foo";

edited Oct 09 '14 at 08:40

tshepang

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answered Sep 05 '14 at 03:47

Christopher Davies

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Sorry, I don't see how to apply your answer to the question. Could you show how to implement his actual abcd and Message example? – Doradus Feb 12 '15 at 03:17
Why is it that String can be concatenated with &str, but not 2 Strings? – CMCDragonkai Feb 16 '15 at 02:59

score 6 · Accepted Answer · edited Oct 09 '14 at 08:41

6

By default string literals have static lifetime, and it is not possible to concatenate unique and static vectors. Using unique literal string helped:

fn main() {
    let x = ~"abcd";
    io::println(~"Message: " + x);
}

edited Oct 09 '14 at 08:41

tshepang

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answered Apr 14 '13 at 08:40

Vladimir Matveev

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score 2 · Answer 3 · answered Apr 20 '13 at 13:07

2

Just to addon to the above answer, as long as the right most string is of the type ~str then you can add any kind of string to it.

let x = ~"Hello" + @" " + &"World" + "!";

answered Apr 20 '13 at 13:07

Luqman

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Concatenate string literal with another string

3 Answers3

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