Learn X By Example
Learn X By Example

    Go by Example: Pointers

    Go by Example : Pointers

    Go supports pointers , allowing you to pass references to values and records within your program.

    package main
    import "fmt"

    We’ll show how pointers work in contrast to values with 2 functions: zeroval and zeroptr . zeroval has an int parameter, so arguments will be passed to it by value. zeroval will get a copy of ival distinct from the one in the calling function.

    func zeroval(ival int) {
    ival = 0
}

    zeroptr in contrast has an *int parameter, meaning that it takes an int pointer. The *iptr code in the function body then dereferences the pointer from its memory address to the current value at that address. Assigning a value to a dereferenced pointer changes the value at the referenced address.

    func zeroptr(iptr *int) {
    *iptr = 0
}
    func main() {
    i := 1
    fmt.Println("initial:", i)
        zeroval(i)
    fmt.Println("zeroval:", i)

    The &i syntax gives the memory address of i , i.e. a pointer to i .

        zeroptr(&i)
    fmt.Println("zeroptr:", i)

    Pointers can be printed too.

        fmt.Println("pointer:", &i)
}

    zeroval doesn’t change the i in main , but zeroptr does because it has a reference to the memory address for that variable.

    $ go run pointers.go
initial: 1
zeroval: 1
zeroptr: 0
pointer: 0x42131100

    Next example: Strings and Runes .

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