http://golang.org/ref/spec#RangeClause
RangeClause = ( ExpressionList "=" | IdentifierList ":=" ) "range" Expression .
Trying to understand the range clause and specifically the difference between an identifier and an expression
Thanks.
With the range keyword you can iterate over many things and assign the results while doing so. You can assign to two things:
IdentifierList)ExpressionList)These are new variables for use in the inner loop. They must obey the rules for identifiers (unicode names, no whitespaces, etc.). If you use these you have to use the := operator between the list an the range keyword.
Example:
for i := range []int{1,2,3} {
fmt.Println(i)
}
You don't necessarily need to declare new variables, you can use existing ones and even have expressions evaluated which return the storage location. A few examples:
Assign to a pointer (Play):
var i = 0
func main() {
p := &i
for *p = range []int{1,2,3} {
fmt.Println(i)
}
}
Return a pointer and assign it (Play):
var i = 0
func foo() *int {
return &i
}
func main() {
for *foo() = range []int{1,2,3} {
fmt.Println(i)
}
}