将接口{}转换为int
将接口{}转换为int
提问于 2013-08-04 17:00:20
我试图从JSON中获取一个值并将其转换为int，但它不起作用，而且我不知道如何正确执行此操作。
以下是错误消息：
...cannot convert val (type interface {}) to type int: need type assertion和代码：
var f interface{}
err = json.Unmarshal([]byte(jsonStr), &f)
if err != nil {
utility.CreateErrorResponse(w, "Error: failed to parse JSON data.")
return
}
m := f.(map[string]interface{})
val, ok := m["area_id"]
if !ok {
utility.CreateErrorResponse(w, "Error: Area ID is missing from submitted data.")
return
}
fmt.Fprintf(w, "Type = %v", val) // <--- Type = float64
iAreaId := int(val) // <--- Error on this line.
testName := "Area_" + iAreaId // not reaching here回答 8
Stack Overflow用户
发布于 2015-04-17 12:30:28
我假设:如果你通过浏览器发送JSON值，那么你发送的任何数字都将是float64类型，所以你不能直接在golang中获取该值。
因此，转换如下所示：
//As that says:
fmt.Fprintf(w, "Type = %v", val) // <--- Type = float64
var iAreaId int = int(val.(float64))这样你就可以得到你想要的精确值。
Stack Overflow用户
发布于 2018-10-16 08:59:18
正在添加另一个使用switch的答案...有更全面的例子，但这将给你一个想法。
在示例中，t成为每个case范围内的指定数据类型。注意，您必须在一个类型中只为一个类型提供一个case，否则t仍然是一个interface。
package main
import "fmt"
func main() {
var val interface{} // your starting value
val = 4
var i int // your final value
switch t := val.(type) {
case int:
fmt.Printf("%d == %T\n", t, t)
i = t
case int8:
fmt.Printf("%d == %T\n", t, t)
i = int(t) // standardizes across systems
case int16:
fmt.Printf("%d == %T\n", t, t)
i = int(t) // standardizes across systems
case int32:
fmt.Printf("%d == %T\n", t, t)
i = int(t) // standardizes across systems
case int64:
fmt.Printf("%d == %T\n", t, t)
i = int(t) // standardizes across systems
case bool:
fmt.Printf("%t == %T\n", t, t)
// // not covertible unless...
// if t {
// i = 1
// } else {
// i = 0
// }
case float32:
fmt.Printf("%g == %T\n", t, t)
i = int(t) // standardizes across systems
case float64:
fmt.Printf("%f == %T\n", t, t)
i = int(t) // standardizes across systems
case uint8:
fmt.Printf("%d == %T\n", t, t)
i = int(t) // standardizes across systems
case uint16:
fmt.Printf("%d == %T\n", t, t)
i = int(t) // standardizes across systems
case uint32:
fmt.Printf("%d == %T\n", t, t)
i = int(t) // standardizes across systems
case uint64:
fmt.Printf("%d == %T\n", t, t)
i = int(t) // standardizes across systems
case string:
fmt.Printf("%s == %T\n", t, t)
// gets a little messy...
default:
// what is it then?
fmt.Printf("%v == %T\n", t, t)
}
fmt.Printf("i == %d\n", i)
}Stack Overflow用户
发布于 2020-07-08 13:59:11
也许你需要
func TransToString(data interface{}) (res string) {
switch v := data.(type) {
case float64:
res = strconv.FormatFloat(data.(float64), 'f', 6, 64)
case float32:
res = strconv.FormatFloat(float64(data.(float32)), 'f', 6, 32)
case int:
res = strconv.FormatInt(int64(data.(int)), 10)
case int64:
res = strconv.FormatInt(data.(int64), 10)
case uint:
res = strconv.FormatUint(uint64(data.(uint)), 10)
case uint64:
res = strconv.FormatUint(data.(uint64), 10)
case uint32:
res = strconv.FormatUint(uint64(data.(uint32)), 10)
case json.Number:
res = data.(json.Number).String()
case string:
res = data.(string)
case []byte:
res = string(v)
default:
res = ""
}
return
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/18041334
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