1. What is the usage of .()?
In golang, .() is called a type assertion, which can convert a variable of type interface{} into other types, such as string types, integer types, etc. When calling a function, we can use .() to convert function parameters to different types.
2. Basic usage of ()
The basic syntax of .() usage is as follows:
value, ok := interface{}.(Type)Where, value is the converted value, and ok is the return value of a bool type, indicating whether the conversion is successful.
Here is a simple example showing how to convert a variable of type interface{} into a string using .():
func main() {
var i interface{} = "hello"
s := i.(string)
(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. The following 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.
Here is an example that demonstrates how to handle ok values during the conversion of nil type:
func main() {
var i interface{} = nil
_, ok := i.(string)
(ok) // false
}The output result is:
false
3.2 Passing a function as a parameter
In golang, functions can be passed as parameters to other functions. .() is very useful if we need to convert function parameters (i.e., parameters of function calls) to different types when we call a function.
Here is an example that demonstrates how to convert function parameters to integer types using .():
func main() {
f := func(i int) {
(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 the integer type "2" as a function parameter to the function test and use .() in the function test to convert it to the int type so that it can be passed to the function f.
4. Notes on use. ()
The following points should be paid attention to when using .():
If we try to convert a non-pointer type variable into a pointer type, then .() will result in panic;
If we try to convert a non-slice type variable into a slice type, then .() will result in panic;
Therefore, you need to be very careful when using .(), follow programming best practices, and test and check as much code as possible.
5. Summary
To sum up, the usage of .() in golang is a very useful feature, which allows us to convert function parameters to different types when calling. In actual development, we can use .() to handle different scenarios according to different needs.
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