我需要将一个整数文件读取到数组中。我用它来处理这个:
package main
import (
"fmt"
"io"
"os"
)
func readFile(filePath string) (numbers []int) {
fd, err := os.Open(filePath)
if err != nil {
panic(fmt.Sprintf("open %s: %v", filePath, err))
}
var line int
for {
_, err := fmt.Fscanf(fd, "%dn", &line)
if err != nil {
fmt.Println(err)
if err == io.EOF {
return
}
panic(fmt.Sprintf("Scan Failed %s: %v", filePath, err))
}
numbers = append(numbers, line)
}
return
}
func main() {
numbers := readFile("numbers.txt")
fmt.Println(len(numbers))
}
文件numbers.txt只是:
1
2
3
...
ReadFile()
似乎太长(可能是由于处理错误)。
有没有一种较短/较常用的加载文件的方法?
使用bufio.Scanner
会让事情变得很好。我还使用了io.Reader
,而不是使用文件名。这通常是一种很好的技术,因为它允许在任何类似文件的对象上使用代码,而不仅仅是磁盘上的文件。这是从字符串中"读取"。
package main
import (
"bufio"
"fmt"
"io"
"strconv"
"strings"
)
// ReadInts reads whitespace-separated ints from r. If there's an error, it
// returns the ints successfully read so far as well as the error value.
func ReadInts(r io.Reader) ([]int, error) {
scanner := bufio.NewScanner(r)
scanner.Split(bufio.ScanWords)
var result []int
for scanner.Scan() {
x, err := strconv.Atoi(scanner.Text())
if err != nil {
return result, err
}
result = append(result, x)
}
return result, scanner.Err()
}
func main() {
tf := "1n2n3n4n5n6"
ints, err := ReadInts(strings.NewReader(tf))
fmt.Println(ints, err)
}
我会这样做:
package main
import (
"fmt"
"io/ioutil"
"strconv"
"strings"
)
// It would be better for such a function to return error, instead of handling
// it on their own.
func readFile(fname string) (nums []int, err error) {
b, err := ioutil.ReadFile(fname)
if err != nil { return nil, err }
lines := strings.Split(string(b), "n")
// Assign cap to avoid resize on every append.
nums = make([]int, 0, len(lines))
for _, l := range lines {
// Empty line occurs at the end of the file when we use Split.
if len(l) == 0 { continue }
// Atoi better suits the job when we know exactly what we're dealing
// with. Scanf is the more general option.
n, err := strconv.Atoi(l)
if err != nil { return nil, err }
nums = append(nums, n)
}
return nums, nil
}
func main() {
nums, err := readFile("numbers.txt")
if err != nil { panic(err) }
fmt.Println(len(nums))
}
您的fmt解决方案。Fscanf很好。当然,根据你的情况,还有很多其他方法可以做。莫斯塔法的技术是我经常使用的(尽管我可能会用make一次分配结果。哎呀!他做到了。)但为了最终控制,你应该学习bufio。ReadLine。请参阅go readline->一些示例代码的字符串。