Golang function return value rules

Go functions can receive multiple parameters and can return zero to multiple values. Return value rules: When there is no explicit return, nil is returned by default. A function cannot return any value when no return value is declared. When there are multiple return values, all values ​​need to be returned at the same time. When declaring an error return value, it must return nil or error with error information.

Go function return value rules

Input parameters and return value

In Go language, functions can receive multiple parameters and can return zero or more values. The types of parameters and return values ​​must be explicitly declared in the function signature.

Return value rules

The return value rules of Go functions are as follows:

• If the function does not return explicitly, it is considered to returnnil.
• If the function declaration does not contain a return value, the function cannot return any value.
• If a function declaration contains multiple return values, all of them must be returned at the same time.
• If the function declaration contains a return value of type error, the function must return nil or error containing error information.

Practical case: Calculating the maximum value

The following is a practical case demonstrating how to use the return value rule:

package main

import "fmt"

// 返回最大值的函数
func max(a, b int) (max int, err error) {
    if a > b {
        return a, nil
    } else if b > a {
        return b, nil
    } else {
        return 0, fmt.Errorf("无法确定最大值：a 和 b 相等")
    }
}

func main() {
    // 调用 max 函数并处理返回值
    x, err := max(10, 20)
    if err != nil {
        fmt.Println(err)
    } else {
        fmt.Println("最大值：", x)
    }
}

In the above Example:

• Functionmax returns two values: the largest element and an error.
• main The function calls max and uses variables x and err to receive the return value.
• If the function returns an error, it will be printed. Otherwise, the largest element will be printed.

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