英文:
Reading and working with an external file in the Go programming language
问题
我一直通过解决一些欧拉项目的问题来学习Go编程语言。我现在正在解决[问题13]（http://projecteuler.net/problem=13）。它包含一个包含100行50位数字的外部文件。我的问题是：如何将这个文件读入Go程序并进行处理？Go语言有一个readlines函数吗？我已经阅读了关于io和ioutil包的资料，我能想到的就是读取文件并打印它；然而，我不确定如何处理这个文件...它可以赋值给一个变量吗？是否有readlines函数等等...
任何帮助将不胜感激。
以下是我目前的代码：
package main
import "fmt"
import "io/ioutil"
func main() {
fmt.Println(ioutil.ReadFile("one-hundred_50.txt"))
}
英文:
I have been learning the Go programming language by doing some of the Project Euler problems. I am now on [problem 13] (<http://projecteuler.net/problem=13>). It contains an external file with 100 lines of 50 digit numbers. My question is: How can this file be read into a Go program and worked with? Does Go have a readlines function? I've read about the io and ioutil packages, and about all I can come up with is reading in the file and printing it; however, I am not sure how to work with the file... Can it be assigned to a variable? Is there a readlines function, etc...
Any help would be appreaciated.
Here is what I have so far:
package main
import "fmt"
import "io/ioutil"
func main() {
fmt.Println(ioutil.ReadFile("one-hundred_50.txt"))
}
答案1
得分: 3
有方法可以逐行读取文件（如果在这里搜索，会有示例），但是真正的ioutil.ReadFile是一个很好的开始。当然你可以将它赋值给一个变量。看一下ReadFile的函数签名，看看它是如何同时返回一个字节切片和一个错误的。同时赋值；检查错误是否为nil。如果不是nil，则打印错误，以便查看出了什么问题。然后，一旦你将字节存储在一个变量中，尝试按行分割它。尝试使用bytes.Split，或者更简单地将其转换为字符串并使用strings.Split。
英文:
There are ways to read a file line by line (and there are examples if you search here on SO) but really ioutil.ReadFile is a good start there. Sure you can assign it to a variable. Look at the function signature for ReadFile and see how it returns both a byte slice and an error. Assign both; check that the error is nil. Print the error if it's not nil so you can see what's wrong. Then once you have the bytes in a variable, try spitting it up by lines. Try bytes.Split, or easier, convert it to a string and use strings.Split.
答案2
得分: 1
对于这个欧拉问题，你可以使用ReadString：
package main
import (
"os"
"bufio"
"fmt"
)
func main() {
r := bufio.NewReader(os.Stdin)
line, err := r.ReadString('\n')
for i := 1; err == nil; i++ {
fmt.Printf("第%d行：%s", i, line)
line, err = r.ReadString('\n')
}
}
使用方法：
go run solution.go < inputfile
英文:
Check out bufio. This answer uses it to read the entire file into memory.
For this Euler problem you can just use ReadString:
package main
import (
"os"
"bufio"
"fmt"
)
func main() {
r := bufio.NewReader(os.Stdin)
line, err := r.ReadString('\n')
for i := 1; err == nil; i++ {
fmt.Printf("Line %d: %s", i, line)
line, err = r.ReadString('\n')
}
}
To use:
go run solution.go < inputfile
答案3
得分: 0
自从这个问题被提出和回答之后，bufio包已经更新（适用于Go 1.1），现在可能有更好的解决方案可用（尽管这些解决方案都不错）。
bufio包中的Scanner类型使得这个问题变得非常简单：
func main() {
f, e := os.Open("one-hundred_50.txt")
if e != nil {
// 处理打开文件时的错误
}
s := bufio.NewScanner(f)
for s.Scan() {
// scanner.Text() 包含当前行的内容
}
if e = s.Err(); e != nil {
// 扫描时出错；在EOF时没有错误
}
}
英文:
Since this question was asked and answered the bufio package has been updated (for Go 1.1) and perhaps a nicer solution is now available (not that any of these are bad).
The Scanner type from the bufio package makes this really easy:
func main() {
f, e := os.Open("one-hundred_50.txt")
if e != nil {
// error opening file, handle it
}
s := bufio.NewScanner(f)
for s.Scan() {
// scanner.Text() contains the current line
}
if e = s.Err(); e != nil {
// error while scanning; no error at EOF
}
}
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论