Use cases for golang function return values

Common use cases for Go function return values ​​include: 1. Passing errors; 2. Returning multiple results; 3. Returning named return values; 4. Using anonymous return values. By returning errors, functions can handle errors conveniently; by returning multiple values, the number of function calls can be reduced; named return values ​​improve code readability; anonymous return values ​​are used to return multiple unnamed values.

#Use cases for Go function return values

Function in Go language can return one or more values, which is very useful in many situations. Here are some common use cases for Go function return values:

1. Passing errors

Go functions usually use the built-in error type to report errors . Passing errors via function return values ​​makes handling errors convenient. For example:

func openFile(filename string) (*os.File, error) {
    file, err := os.Open(filename)
    return file, err
}

2. Return multiple results

The function can return multiple values ​​to reduce the number of nested function calls. For example:

func minMax(numbers []int) (int, int) {
    min := numbers[0]
    max := numbers[0]
    for _, num := range numbers {
        if num < min {
            min = num
        }
        if num > max {
            max = num
        }
    }
    return min, max
}

3. Return named return values

Go functions can also return named return values, which helps improve the readability and maintainability of the code . For example:

type Coordinates struct {
    Lat float64
    Lon float64
}

func getCoordinates(address string) (Coordinates, error) {
    // ... 解析地址并获取坐标
    return Coordinates{Lat: 12.345, Lon: 56.789}, nil
}

4. Use anonymous return values ​​

Anonymous return values ​​are used when a function needs to return multiple values, but there is no need to specify names for them. For example:

func findIndex(slice []int, value int) int {
    for i, v := range slice {
        if v == value {
            return i
        }
    }
    return -1
}

Practical case

The following is a practical case of using function return value to handle errors:

package main

import (
    "fmt"
    "io/ioutil"
)

func readFile(filename string) (string, error) {
    data, err := ioutil.ReadFile(filename)
    return string(data), err
}

func main() {
    filename := "file.txt"
    content, err := readFile(filename)
    if err != nil {
        fmt.Println("Error reading file:", err)
    } else {
        fmt.Println("File contents:", content)
    }
}

In the above example,# The ##readFile function returns the file contents and an error value. If reading the file is successful, the file contents will be printed. If the read fails, an error message will be printed.

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