Can Golang function return values ​​be cast?

Go language allows function return value coercion, and its syntax format is value := variable.(targetType). Casting can be used to convert a value of type interface{} to a specific type, such as map[string]string. Considerations include type compatibility, value validation, and careful use.

Forced type conversion function return value in Go

In Go language, function return value can be forced type conversion. The syntax format is as follows:

value := variable.(targetType)

where:

• variable is the variable to be converted.
• targetType is the target type to be converted.

Practical case:

Suppose there is a GetUserInfo function, which returns an interface{} type map:

func GetUserInfo() interface{} {
    return map[string]string{"name": "John Doe", "age": "30"}
}

To cast this return value to the map[string]string type, you can use the following code:

userInfo := GetUserInfo().(map[string]string)

Now, userInfo The variable is a variable of type map[string]string, which can be used like a normal map:

fmt.Println(userInfo["name"]) // 输出：John Doe

Notes:

• Casting only works on compatible types. If the types being converted are incompatible, a runtime error is thrown.
• Forced type conversion only checks the type of the variable and does not perform any verification on its value. For example, if the variable being converted contains an invalid value, the cast may still succeed, but an error will occur when using the value.
• Be careful when using casts. If the conversion type is incorrect, it may cause the program to behave unpredictably.

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