2018-01-16 22:06
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I am new to go language, under learning. I have years OOP experience in C++. There is a stacker interface that is written in go and two implementations of it, one is slice base stack and another one is linkedlist base.

I find it is hard to compare two different structures and tell if they are containing the same data or not. The simple example code list below (notice a lot of functions/implementations are not listed because they are not relative with this question). The key function is stackEquals, I have tried different ways to approach it but they failed. Please see the comments in the code.

package main

import (

// The interface is fixed, cannot be modified
type Stacker interface {
    isEmpty() bool
    size() int
    push(x int)
    peek() (int, error)
    pop() (int, error)
    copy() Stacker

type StackSlice struct {
    slice []int

type StackLinked struct {
    next *StackLinked
    value int
    // possible with other variables that is not relative

// There are interface function/method implementations did not paste

func (s StackSlice) String() string {
    // return all the value inside the stack as string
    // like [5 4]

func (s StackLinked) String() string {
    // return all the value inside the stack as string
    // like [5 4]]

// Pre-condition:
//    none
// Post-condition:
//    returns true if s and t have the same elements in the same order;
//    both s and t have the same value after calling stackEquals as before
// Annoying constraint:
//    Use only Stackers in the body of this functions: don't use arrays,
//    slices, or any container other than a Stacker.
func stackEquals(s, t Stacker) bool {
    // This implementation below always return false unless they are the same thing
    return s == t 

    // I tried return s.String() == t.String() but gave an error said interface doesn't have String() method.

How can I compare two stacks that implemented in different way and tell if they are the same (same means same values in same order) in the stack.

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我是初学者,正在学习中。 我有多年C ++ OOP经验。 有一个用go编写的堆栈器接口,它有两个实现,一个是切片基堆栈,另一个是链表基。

我发现很难比较两种不同的结构, 告诉他们是否包含相同的数据。 下面是简单的示例代码列表(注意,未列出许多功能/实现,因为它们与该问题无关)。 关键功能是 stackEquals ,我尝试了不同的方法来实现它,但是失败了。 请参阅代码中的注释。

“ fmt” 
“ errors” 
 // 是固定的,无法修改
type Stacker接口{
 push(x int)
type StackSlice结构{
 slice [] int 
type StackLinked结构{
 next * StackLinked 
 value int 
 //可以与其他变量一起使用 不是相对的
func(s StackSlice)String()string {
  //像[5 4] 
func(s StackLinked)String()string {
 //像[5 4]] 
} \  n 
 // s和t都具有 调用stackE之后的值与之前相同\  n //烦人的约束:
func stackEquals(s,t Stacker)bool  {
 return s == t 
 //我尝试返回s.String()== t.String(),但给出了错误提示 接口没有String()方法。

如何比较以不同方式实现的两个堆栈,并判断它们是否相同(相同 表示相同的值(顺序相同)。

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1条回答 默认 最新

  • doutui7955 2018-01-17 01:21

    If you need to compare two interfaces, you can only use the methods in that interface, so in this case, String does not exist in the interface (even though both of your implementations have it, the interface itself does not).

    A possible implementation would be:

    func stackEquals(s, t Stacker) bool {
        // if they are the same object, return true
        if s == t {
            return true
        // if they have different sizes or the next element is not the same,
        // then they are different
        if s.size() != t.size() || s.peek() != t.peek() {
            return false
        // they could be the same, so let's copy them so that we don't mess up
        // the originals
        ss = s.copy()
        tt = t.copy()
        // iterate through the values and check if each one is
        // the same.  If not, return false
        for ; i, err := ss.pop(); err == nil {
            if j, err := tt.pop(); err != nil || i != j {
                return false
        return true

    This assumes that the only error pop would get is when there are no more values, otherwise you will need to do some better error checking and use isEmpty.

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