英文:
How to prevent/fix panic: runtime error: invalid memory address or nil pointer dereference
问题
我是你的中文翻译助手，以下是翻译好的内容：
我对golang还不熟悉。从下面的代码来看，有时color可能为nil，但我仍然需要调用GetCategory函数。这会导致以下错误：
panic: runtime error: invalid memory address or nil pointer dereference
如何优雅地调用GetCategory函数并避免这个错误？
非常感谢您的帮助！
package mainimport ("fmt""strings")type event struct {color *stringCategory *string}func GetCategory(color string) (*string, error) {var category stringif strings.HasPrefix(color, "red") {category = "likes"} else if strings.HasPrefix(color, "blue") {category = "dislikes"}return &category, nil}func main() {category := "red"eventObj := event{Category: &category,}if eventObj.color != nil {fmt.Println(GetCategory(*eventObj.color))} else {fmt.Println("color is nil")}}
英文:
I'm new to golang. From the code below, sometimes color could be nil, but I still need to call GetCategory. This would result in the err below:
panic: runtime error: invalid memory address or nil pointer dereference
How to call GetCategory gracefully and avoid the err?
Thanks in advance for any help!
import ("fmt""strings")type event struct {color *stringCategory *string}func GetCategory(color string) (*string, error) {var category stringif strings.HasPrefix(color, "red") {category = "likes"} else if strings.HasPrefix(color, "blue") {category = "dislikes"}return &category, nil}func main() {category := "red"eventObj := event{Category: &category,}fmt.Println(GetCategory(*eventObj.color))}</details># 答案1**得分**: 2如果你需要检查某个东西是否为nil，你只需要*这样做*，然后相应地采取行动。例如：```gofunc GetCategory(color *string) (*string, error) {if color == nil {return nil, errors.New("Color is nil")}// ...
如果某个东西可能为nil，你只需在使用之前使用简单的相等或不等检查(== nil或!= nil)来检查是否为nil。
英文:
If you need to check if something is nil, you just do that, and act accordingly. For example:
func GetCategory(color *string) (*string, error) {if color == nil {return nil, errors.New("Color is nil")}// ...
There is no elvis operator, safe navigation operator, optional chaining etc.
If something might be nil, you simply check for nil with a straightforward equality or inequality check (== nil or != nil) before you use it.
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