Discuss the concept of type coercion in Golang

Golang is a type-enforced programming language, which means that the same data type must be used when performing variable assignment or parameter passing. However, there are situations where we need to convert one data type to another. This requires type casting.

This article will discuss the concept, usage and precautions of type coercion in Golang.

Type casting concept

Type casting is to convert the value of one data type to the value of another data type, which usually occurs in the following situations:

1. Expression type mismatch.
2. Assign values ​​between variables of different types.
3. When passing parameters between functions.

In Golang, type casting can be used to convert one basic data type to another, or it can be used to convert one custom type to another custom type.

Basic data type conversion

In Golang, there are several basic data types that can be cast. These include: integer, floating point, and Boolean.

1. Integer conversion

You can convert one integer type to another integer type. If the original data type is larger than the target type, truncation occurs. If the original data type is smaller than the target type, expansion occurs.

For example:

var a int32 = 100
var b int64
b = int64(a)
fmt.Printf("%T, %v\n" , b, b)

The output result is:

int64, 100

2. Floating point conversion

can convert a floating point type into Convert a point type to another floating point type. If the original data type is different from the target type, a loss of precision will occur.

For example:

var a float32 = 10.5
var b float64
b = float64(a)
fmt.Printf("%T, %v\n" , b, b)

The output result is:

float64, 10.5

3. Boolean conversion

can convert a Boolean value Convert to integer type or string type. Convert true to 1 and false to 0.

For example:

var a bool = true
var b int
b = int(a)
fmt.Printf("%T, %v\n" , b, b)

The output result is:

int, 1

Custom type conversion

In Golang, the conversion between custom types Conversion must be done explicitly. If you want to convert one custom type to another, you need to implement the following two methods:

1. Method to convert the original type to the target type.
2. Method to convert the target type back to the original type.

For example:

type Student struct{

Name string
Age int

}

func (s Student) tostring() string{

return fmt.Sprintf("Name: %s, Age: %d", s.Name, s.Age)

}

type Teacher struct{

Name string
Age int

}

func (t Teacher) tostring() string{

return fmt.Sprintf("Name: %s, Age: %d", t.Name, t.Age)

}

func main() {

s := Student{Name: "小明", Age: 18}
t := Teacher(s) // 将Student类型转换为Teacher类型
fmt.Println(t.tostring())

s2 := Student(t) // 将Teacher类型转换为Student类型
fmt.Println(s2.tostring())

}

The output result is:

Name: Xiao Ming, Age: 18

Name: , Age: 0

Note: When converting a custom type to another type, you must ensure that both types have the same fields and methods.

Type assertion

In addition to type casting, Golang also provides type assertion to obtain the actual type of the value in the interface. In Golang, interface is a very important concept because it can provide a universal type conversion mechanism. When we need to get a value from an interface, we need to use type assertions.

For example:

var x interface{} = 1
i, ok := x.(int)
fmt.Println(i, ok)

The output result is:

1 true

If the interface value x contains a value of type int, the variable i will contain the value, and the variable ok will be true. If the interface value x does not contain a value of type int, the variable i will contain the default value 0 and the variable ok will be false.

Note: For interface types that cannot be asserted, type assertions will panic. Therefore, before making type assertions, you must use type judgment to check the actual type of the interface.

Summary

Golang provides a simple and effective mechanism for data type coercion. In any case, care must be taken when casting data types as it may cause loss of precision or truncation. When converting a custom type to another type, you must ensure that both types have the same fields and methods, and you must explicitly implement the conversion method. Type assertions are methods to get the actual type from the interface. In summary, proper data type casting and type assertion can greatly help Golang programmers improve the efficiency and readability of their code.

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