Detailed introduction to the use of .() in golang

Golang is a very popular programming language and is widely used in many fields. During the development process, many times we need to pass functions as parameters to other functions. At this time, we need to use the .() usage in golang. This article will introduce in detail the use of .() in golang.

1. What is the usage of .()?
   In golang, .() is called a type assertion, which can convert a variable of interface{} type into other types, such as string type, integer type, etc. When calling a function, we can use .() to convert function parameters to different types.

2. .The basic usage of ()
   .The basic syntax of () usage is as follows:

   value, ok := interface{}.(Type)

   Among them, value is the converted value, and ok is a bool type return Value indicating whether the conversion was successful.

The following is a simple example that shows how to use .() to convert an interface{} type variable into a string type:

func main() {
    var i interface{} = "hello"
    s := i.(string)
    fmt.Println(s)
}

The output result is :

hello

3. . Advanced application of () usage
   .() is very flexible to use and can play an important role in different scenarios of the program. Below are two advanced application scenarios.

3.1 Conversion of nil type
The nil type is very common in golang. It can represent pointer types, slice types, etc. During the type conversion process, we need to pay attention to handling the nil type. In this case, we need to use the ok value to determine whether the conversion is successful.

The following is an example that demonstrates how to handle ok values ​​during conversion to nil type:

func main() {
    var i interface{} = nil
    _, ok := i.(string)
    fmt.Println(ok) // false
}

The output result is:

false

3.2 Passing functions as parameters
In golang, functions can be passed as parameters to other functions. .() is very useful if we need to convert the function parameters (i.e. the parameters of the function call) to different types when calling the function.

The following is an example that demonstrates how to use .() to convert function parameters to integer types:

func main() {
    f := func(i int) {
        fmt.Println(i)
    }
    test(f, "2")
}

func test(f func(int), s interface{}) {
    if i, ok := s.(int); ok {
        f(i)
    }
}

The output result is:

2

In this example, we Pass "2" of integer type as a function parameter to function test, and use .() in function test to convert it to type int so that it can be passed to function f.

4. Precautions when using .()
   You need to pay attention to the following points when using .():

• If we try to convert a non- If a pointer type variable is converted to a pointer type, then .() will cause panic;
• If we try to convert a non-slice type variable to a slice type, then .() will cause panic;
  Therefore, you need to be very careful when using .(), follow programming best practices, and test and check the code as much as possible.

To sum up, the .() usage in golang is a very useful feature, which allows us to convert function parameters into different types when the function is called. In actual development, we can use .() to handle different scenarios according to different needs.

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