Golang 提供了一个庞大的内置库，可用于对文件执行读写操作。为了读取本地系统上的文件，使用了io/ioutil模块。 io/ioutil模块也用于将内容写入文件。
fmt模块使用函数实现格式化 I/O，以从 stdin 读取输入并将输出打印到 stdout。 log模块实现了简单的日志包。它定义了一个类型 Logger，以及用于格式化输出的方法。 os模块提供访问本机操作系统功能的能力。 bufio模块实现缓冲 I/O，有助于提高 CPU 性能。
- os.Create() ： os.Create() 方法用于创建具有所需名称的文件。如果已存在同名文件，则 create函数截断该文件。
- ioutil.ReadFile() ： ioutil.ReadFile() 方法采用要读取的文件的路径，因为它是唯一的参数。此方法返回文件的数据或错误。
- ioutil.WriteFile() ： ioutil.WriteFile() 用于将数据写入文件。 WriteFile() 方法接受 3 个不同的参数，第一个是我们希望写入的文件的位置，第二个是数据对象，第三个是 FileMode，它表示文件的模式和权限位。
- log.Fatalf ： Fatalf 将在打印日志消息后导致程序终止。它等价于 Printf() 之后调用 os.Exit(1)。
- log.Panicf : Panic 就像一个可能在运行时出现的异常。 Panicln 等价于 Println() 之后调用 panic()。传递给 panic() 的参数将在程序终止时打印出来。
- bufio.NewReader(os.Stdin) ：此方法返回一个新的 Reader，其缓冲区具有默认大小（4096 字节）。
- inputReader.ReadString(‘\n’) ：此方法用于从 stdin 读取用户输入并读取直到输入中第一次出现分隔符，返回一个包含数据的字符串，直到并包括分隔符。如果在找到定界符之前遇到错误，它会返回错误之前读取的数据和错误本身。
示例 1：使用离线编译器以获得更好的结果。使用.go扩展名保存文件。使用下面的命令来执行程序。
go run filename.go// Golang program to read and write the files
package main
// importing the packages
import (
"fmt"
"io/ioutil"
"log"
"os"
)
func CreateFile() {
// fmt package implements formatted
// I/O and has functions like Printf
// and Scanf
fmt.Printf("Writing to a file in Go lang\n")
// in case an error is thrown it is received
// by the err variable and Fatalf method of
// log prints the error message and stops
// program execution
file, err := os.Create("test.txt")
if err != nil {
log.Fatalf("failed creating file: %s", err)
}
// Defer is used for purposes of cleanup like
// closing a running file after the file has
// been written and main //function has
// completed execution
defer file.Close()
// len variable captures the length
// of the string written to the file.
len, err := file.WriteString("Welcome to GeeksforGeeks."+
" This program demonstrates reading and writing"+
" operations to a file in Go lang.")
if err != nil {
log.Fatalf("failed writing to file: %s", err)
}
// Name() method returns the name of the
// file as presented to Create() method.
fmt.Printf("\nFile Name: %s", file.Name())
fmt.Printf("\nLength: %d bytes", len)
}
func ReadFile() {
fmt.Printf("\n\nReading a file in Go lang\n")
fileName := "test.txt"
// The ioutil package contains inbuilt
// methods like ReadFile that reads the
// filename and returns the contents.
data, err := ioutil.ReadFile("test.txt")
if err != nil {
log.Panicf("failed reading data from file: %s", err)
}
fmt.Printf("\nFile Name: %s", fileName)
fmt.Printf("\nSize: %d bytes", len(data))
fmt.Printf("\nData: %s", data)
}
// main function
func main() {
CreateFile()
ReadFile()
}// Golang program to read and write the files
package main
// importing the requires packages
import (
"bufio"
"fmt"
"io/ioutil"
"log"
"os"
)
func CreateFile(filename, text string) {
// fmt package implements formatted I/O and
// contains inbuilt methods like Printf
// and Scanf
fmt.Printf("Writing to a file in Go lang\n")
// Creating the file using Create() method
// with user inputted filename and err
// variable catches any error thrown
file, err := os.Create(filename)
if err != nil {
log.Fatalf("failed creating file: %s", err)
}
// closing the running file after the main
// method has completed execution and
// the writing to the file is complete
defer file.Close()
// writing data to the file using
// WriteString() method and the
// length of the string is stored
// in len variable
len, err := file.WriteString(text)
if err != nil {
log.Fatalf("failed writing to file: %s", err)
}
fmt.Printf("\nFile Name: %s", file.Name())
fmt.Printf("\nLength: %d bytes", len)
}
func ReadFile(filename string) {
fmt.Printf("\n\nReading a file in Go lang\n")
// file is read using ReadFile()
// method of ioutil package
data, err := ioutil.ReadFile(filename)
// in case of an error the error
// statement is printed and
// program is stopped
if err != nil {
log.Panicf("failed reading data from file: %s", err)
}
fmt.Printf("\nFile Name: %s", filename)
fmt.Printf("\nSize: %d bytes", len(data))
fmt.Printf("\nData: %s", data)
}
// main function
func main() {
// user input for filename
fmt.Println("Enter filename: ")
var filename string
fmt.Scanln(&filename)
// user input for file content
fmt.Println("Enter text: ")
inputReader := bufio.NewReader(os.Stdin)
input, _ := inputReader.ReadString('\n')
// file is created and read
CreateFile(filename, input)
ReadFile(filename)
}输出：
示例 2：接受用户输入以读取和写入文件的 Golang 程序代码。
// Golang program to read and write the files
package main
// importing the requires packages
import (
"bufio"
"fmt"
"io/ioutil"
"log"
"os"
)
func CreateFile(filename, text string) {
// fmt package implements formatted I/O and
// contains inbuilt methods like Printf
// and Scanf
fmt.Printf("Writing to a file in Go lang\n")
// Creating the file using Create() method
// with user inputted filename and err
// variable catches any error thrown
file, err := os.Create(filename)
if err != nil {
log.Fatalf("failed creating file: %s", err)
}
// closing the running file after the main
// method has completed execution and
// the writing to the file is complete
defer file.Close()
// writing data to the file using
// WriteString() method and the
// length of the string is stored
// in len variable
len, err := file.WriteString(text)
if err != nil {
log.Fatalf("failed writing to file: %s", err)
}
fmt.Printf("\nFile Name: %s", file.Name())
fmt.Printf("\nLength: %d bytes", len)
}
func ReadFile(filename string) {
fmt.Printf("\n\nReading a file in Go lang\n")
// file is read using ReadFile()
// method of ioutil package
data, err := ioutil.ReadFile(filename)
// in case of an error the error
// statement is printed and
// program is stopped
if err != nil {
log.Panicf("failed reading data from file: %s", err)
}
fmt.Printf("\nFile Name: %s", filename)
fmt.Printf("\nSize: %d bytes", len(data))
fmt.Printf("\nData: %s", data)
}
// main function
func main() {
// user input for filename
fmt.Println("Enter filename: ")
var filename string
fmt.Scanln(&filename)
// user input for file content
fmt.Println("Enter text: ")
inputReader := bufio.NewReader(os.Stdin)
input, _ := inputReader.ReadString('\n')
// file is created and read
CreateFile(filename, input)
ReadFile(filename)
}
输出：
