Go question: make(map) syntax

[atul khot]

Dear Mark,
Thanks for your answers...
One other thing I felt a little odd was "making of a map"

var m map[string]int = make(map[string]int)

Here, as I understand, the key is a string - and value is an int...

So, does it mean that whatever is in the square brackets ([]) is the type of key - and what immediately follows the closing
] is the type of value...

Is this the correct way to go?

Also,
I solved the gotour exercise no 44 (Exercise: Maps) -
For some reason, I think Go supports post increment - but not per-increment

package main

import (
        "code.google.com/p/go-tour/wc"
        "strings"
)

func WordCount(s string) map[string]int {
        var m map[string]int = make(map[string]int)

        for _, value := range strings.Fields(s) {
                m[value]++ // ++m[value] gives error
        }
        return m
}

func main() {
        wc.Test(WordCount)
}      

--- warm regards
atul

[Mark Summerfield]

Hi Atul,

var m map[string]int = make(map[string]int)

Here, as I understand, the key is a string - and value is an int...

Yes, you are quite right. You can also do it like this:

m := map[string]int{}

or like this if you want it to start out nonempty:

m := map[string]int{"one": 1, "two": 2}

And, of course, you can use other types too.

You are also right that Go only supports post increment, i++. Also, increment is not an expression, so you can not write j = i++ in Go. This avoids lots of potential problems, e.g., f(i++) and f(++i) are legal in C but not in Go.

And in your solution to exercise 44 you return a map that you've allocated inside a function: and this is perfectly good Go style (but would be a disaster in C/C++!) thanks to Go's memory management.