Mastering Rust - Second Edition

Joining strings

Another source of confusion when dealing with strings in Rust is when concatenating two strings. In other languages, you have a very intuitive syntax for joining two strings. You just do "Foo" + "Bar" and you get a "FooBar". Not quite the case with Rust:

// string_concat.rsfn main() {    let a = "Foo";    let b = "Bar";    let c = a + b;}

If we compile this, we get the following error:

The error message is really helpful here. The concatenation operation is a two step process. First, you need to allocate a string and then iterate over both of them to copy their bytes to this newly allocated string. As such, there's an implicit heap ...