英文:
Golang: returning pointers and derefrencing
问题
所以我有一个名为getToken()的函数。
func getToken() jwt.MapClaims {
tokenString := "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VybmFtZSI6ImFkYW0iLCJwYXNzd29yZCI6InRlc3QiLCJpYXQiOjE0ODcyMDY2OTIsImV4cCI6MTUxODc2NDI5Mn0.6LQo_gRwXiFBvNIJOwtf9UuxoQMZZ3XNILTnU-46-Zg"
token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
return nil, fmt.Errorf("Unexpected signing method: %v", token.Header["alg"])
}
hmacSampleSecret := []byte("supersecretkittysecret")
return hmacSampleSecret, nil
})
if err != nil {
println("error")
}
if claims, ok := token.Claims.(jwt.MapClaims); ok && token.Valid {
return claims
} else {
return nil
}
}
然后对应的调用：
res := getToken()
println(res["username"])
为什么res["username"]等于两个内存地址(0x2b3c20,0xc420075420)？它应该只是一个字符串，比如adam。我还尝试过func getToken() *jwt.MapClaims和return &claims，但这仍然没有帮助。
英文:
So I have a function getToken()
func getToken() jwt.MapClaims {
tokenString := "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VybmFtZSI6ImFkYW0iLCJwYXNzd29yZCI6InRlc3QiLCJpYXQiOjE0ODcyMDY2OTIsImV4cCI6MTUxODc2NDI5Mn0.6LQo_gRwXiFBvNIJOwtf9UuxoQMZZ3XNILTnU-46-Zg"
token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
return nil, fmt.Errorf("Unexpected signing method: %v", token.Header["alg"])
}
hmacSampleSecret := []byte("supersecretkittysecret")
return hmacSampleSecret, nil
})
if err != nil {
println("error")
}
if claims, ok := token.Claims.(jwt.MapClaims); ok && token.Valid {
return claims
} else {
return nil
}
}
Then the corresponding call:
res := getToken()
println(res["username"])
Why is res["username"] equal to two memory addresses (0x2b3c20,0xc420075420)? This should just be a string like adam. I have also tried func getToken() *jwt.MapClaims and return &claims, but this still did not help.
答案1
得分: 2
你应该尝试使用fmt.Println而不是println。下面是使用println和fmt.Println打印地图的示例代码：
package main
import (
"fmt"
)
func foo() map[string]string {
return map[string]string{
"k": "value",
}
}
func main() {
res := foo()
println("Output from println:", res) // 打印指针地址
fmt.Println("Output from fmt.Println: ", res) // 打印地图
}
输出：
Output from println: 0x10432200
Output from fmt.Println: map[k:value]
你可以在这里查看代码示例：https://play.golang.org/p/gCNqng3KEE
英文:
You should try using fmt.Println instead of println. Here's an example of printing a map using println vs fmt.Println
package main
import (
"fmt"
)
func foo() map[string]string {
return map[string]string{
"k": "value",
}
}
func main() {
res := foo()
println("Output from println:", res) // prints pointer address
fmt.Println("Output from fmt.Println: ", res) // prints the map
}
https://play.golang.org/p/gCNqng3KEE
Output:
Output from println: 0x10432200
Output from fmt.Println: map[k:value]
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