Use the io/ioutil.ReadFile function to read the file content and return byte slices and error information

Use the io/ioutil.ReadFile function to read the file contents and return byte slices and error information

In the Go language, use the ReadFile function in the io/ioutil package to read the file contents. The signature of this function is as follows:

func ReadFile(filename string) ([]byte, error)

This function receives a string parameter filename, which represents the path of the file to be read. The function returns two values, one is a byte slice ([]byte), indicating the read file content; the other is an error message (error), indicating whether an error occurred while reading the file.

The following example shows how to use the ReadFile function to read the contents of a text file and output it:

package main

import (
    "fmt"
    "io/ioutil"
)

func main() {
    filename := "test.txt"
    content, err := ioutil.ReadFile(filename)
    if err != nil {
        fmt.Printf("读取文件[%s]发生错误：%s
", filename, err.Error())
        return
    }
    fmt.Println(string(content))
}

In the above code, a variable filename is first defined, which is the path of the file to be read. . Then the ioutil.ReadFile function is called, and the returned byte slice is assigned to the variable content, and the error message is assigned to the variable err.

Next, determine whether there is an error in reading the file by judging whether err is nil. If err is not nil, that is, an error occurred while reading the file, the error message will be output through fmt.Printf and returned. Otherwise, convert the byte slice content to a string and output the contents of the file via fmt.Println.

It should be noted that the ReadFile function reads the contents of the entire file and returns it as a byte slice. If you need to read a large file, you should consider using the Scanner or Reader in the bufio package to read the file line by line or in blocks to reduce memory usage.

In summary, through the ReadFile function in the io/ioutil package, we can easily read the contents of the file and perform subsequent processing through the returned byte slices and error information. In actual development, we can further expand this function as needed to meet more reading needs.

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