1.5.3 Declaring Variables

This version of the program uses a short variable declaration to declare and initialize s and sep, but we could equally well have declared the variables separately. There are several ways to declare a string variable; these are all equivalent:

s := ""
var s string
var s = ""
var s string = ""

Why should you prefer one form to another?

• The first form, a short variable declaration, is the most compact, but it may be used only within a function, not for package-level variables.
• The second form relies on default initialization to the zero value for strings, which is “”.
• The third form is rarely used except when declaring multiple variables.
• The fourth form is explicit about the variable’s type, which is redundant when it is the same as that of the initial value but necessary in other cases where they are not of the same type.

In practice, you should generally use one of the first two forms, with explicit initialization to say that the initial value is important and implicit initialization to say that the initial value doesn’t matter.

As noted above, each time around the loop, the string s gets completely new contents. The ‘+=’ statement makes a new string by concatenating the old string, a space character, and the next argument, then assigns the new string to s. The old contents of s are no longer in use, so they will be garbage-collected in due course.