# String concatenation and bang operators

## String concatenation

    xquery version "3.0";

    let $who := "world"
    return
        "Hello " || $who || "!"

## Bang operator

Can be used instead of simple for expressions. The expression to the right of the operator is evaluated once for each item in the left-hand sequence, setting the context item to the current item.

    xquery version "3.0";

    ("Hello", "world") ! upper-case(.)