Learn the reflect.TypeOf function in Go language documentation to implement type reflection

Learn the reflect.TypeOf function in the Go language document to implement type reflection

In the Go language, we can use reflection to obtain the type of a variable. This That's what the reflect.TypeOf function does. Using this function, you can dynamically obtain the type of the variable, and you can also perform corresponding logical processing based on the type of the variable.

Reflection is the basis of many advanced libraries and tools, helping programmers deal with values ​​whose specific types are not known at compile time. The reflect.TypeOf function is one such powerful tool.

When using reflect.TypeOf, you need to pay attention to the following points:

1. The parameter type of the reflect.TypeOf function is interface{}, which means that the function can receive any type of value as Parameters;
2. The reflect.TypeOf function returns a value of type reflect.Type, which represents the actual type of the parameter passed in;

Then, let’s take a look at reflect. Example of using the TypeOf function:

package main

import (
    "fmt"
    "reflect"
)

func main() {
    //定义一个变量
    var i int = 100

    //获取该变量的类型
    t := reflect.TypeOf(i)

    //输出变量的类型
    fmt.Println("TypeOf i:", t)
}

Run the above code, the output result is as follows:

TypeOf i: int

As can be seen from the output result, the reflect.TypeOf function returns a value of type reflect.Type. This The value represents the actual type of the parameter passed in.

In the above example, we passed in an integer variable i, then used the reflect.TypeOf function to obtain the type of the variable, and obtained a value t of type reflect.Type. Finally, the type of the variable is output, and int is obtained.

In addition to the above examples, we can also use the reflect.TypeOf function to obtain the types of other types of variables, such as strings, floating point numbers, complex numbers, structures, etc.:

package main

import (
    "fmt"
    "reflect"
)

func main() {
    //定义一个字符串变量
    var str string = "Hello, World!"

    //获取该字符串变量的类型
    t1 := reflect.TypeOf(str)

    //定义一个浮点数变量
    var f float64 = 3.14

    //获取该浮点数变量的类型
    t2 := reflect.TypeOf(f)

    //定义一个复数变量
    var c complex128 = 1 + 2i

    //获取该复数变量的类型
    t3 := reflect.TypeOf(c)

    //定义一个结构体
    type Person struct {
        name string
        age  int
    }

    //实例化一个 Person 对象
    p := Person{name: "张三", age: 18}

    //获取该 Person 对象的类型
    t4 := reflect.TypeOf(p)

    //输出变量的类型
    fmt.Println("TypeOf str:", t1)
    fmt.Println("TypeOf f:", t2)
    fmt.Println("TypeOf c:", t3)
    fmt.Println("TypeOf p:", t4)
}

Run the above code , the output result is as follows:

TypeOf str: string
TypeOf f: float64
TypeOf c: complex128
TypeOf p: main.Person

It can be seen from the output result that no matter what type the variable is, the result obtained by using the reflect.TypeOf function is correct.

Summary

In the Go language, you can use the reflect.TypeOf function to dynamically obtain the type of a variable, and then perform corresponding logical processing based on the type of the variable. Therefore, reflection is an indispensable skill when writing some advanced libraries and tools. In the process of learning reflection, you need to pay attention to the parameter type and return type of the function, and you also need to pay attention to the performance issues of the reflection function.

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