英文:
Why am I getting "interface conversion: interface is int32" for converting a list integer element to a string?
问题
新手学习Go语言...我写了一个程序来移除存储在列表中的重复整数。当我运行removeDuplicates函数的以下测试时，我得到了以下错误，指向linked_test.go中的这一行：testString += strconv.Itoa(e.Value.(int))。为什么会出现这个错误，我该如何修复它？我在testList中存储整数，并使用e.Value获取它们，并使用*.(int)*进行类型转换。
panic: interface conversion: interface is int32, not int [recovered]panic: interface conversion: interface is int32, not int
linked_test.go
package linkedimport ("container/list""strconv""testing")func TestDuplicates(t *testing.T) {var (testList = list.New()exampleList = list.New()testString string = "")testList.PushBack(1)testList.PushBack(2)testList.PushBack(3)testList.PushBack(2)exampleList = removeDuplicates(testList)for e := exampleList.Front(); e.Next() != nil; e = e.Next() {testString += strconv.Itoa(e.Value.(int))}if testString != "123" {t.Fatalf("removeDuplicates failed")}}
linked.go
package linkedimport ("container/list""strconv""strings")func removeDuplicates(l *list.List) *list.List {var newList = list.New()var dupString string = ""for e := l.Front(); e.Next() != nil; e = e.Next() {if strings.Index(dupString, strconv.Itoa(e.Value.(int))) == -1 {dupString += strconv.Itoa(e.Value.(int))}}for _, c := range dupString {newList.PushBack(c)}return newList}
英文:
New to Go...I wrote a program to remove duplicate integers stored in a list. When I run the following test for the removeDuplicates function, I get the following error which points to this line: testString += strconv.Itoa(e.Value.(int)) in linked_test.go. Why is this and how do I fix it? I store integers in testList and fetch them with e.Value and typecast with .(int).
panic: interface conversion: interface is int32, not int [recovered]panic: interface conversion: interface is int32, not int
linked_test.go
package linkedimport ("container/list""strconv""testing")func TestDuplicates(t *testing.T) {var (testList = list.New()exampleList = list.New()testString string = "")testList.PushBack(1)testList.PushBack(2)testList.PushBack(3)testList.PushBack(2)exampleList = removeDuplicates(testList)for e := exampleList.Front(); e.Next() != nil; e = e.Next() {testString += strconv.Itoa(e.Value.(int))}if testString != "123" {t.Fatalf("removeDuplicates failed")}}
linked.go
package linkedimport ("container/list""strconv""strings")func removeDuplicates(l *list.List) *list.List {var newList = list.New()var dupString string = ""for e := l.Front(); e.Next() != nil; e = e.Next() {if strings.Index(dupString, strconv.Itoa(e.Value.(int))) == -1 {dupString += strconv.Itoa(e.Value.(int))}}for _, c := range dupString {newList.PushBack(c)}return newList}
答案1
得分: 1
rune被别名为int32，
for _, c := range dupString {newList.PushBack(c) // c是一个rune，也就是int32类型}
在这里推入的是int32类型的值，而在64位CPU上，int被别名为int64，所以一种方法是强制类型转换：
for _, c := range dupString {newList.PushBack(int(c))}
英文:
rune is aliased to int32,
for _, c := range dupString {newList.PushBack(c) // c is a rune aka int32}
is pushing int32s, while int is aliased to int64 on 64bit CPUs, so one way to do it is to just force the type:
for _, c := range dupString {newList.PushBack(int(c))}
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