如何使用Golang在文件中写入整数？

Question

1. I generate numbers from 0 to 10
2. I create a file
3. And I try to write to the file by converting integers to string

But when I open the h.txt file there is nothing written

How to fix this and have the numbers written to the h.txt file?

package main

import "os"

func main() {
    for i := 0; i < 10; i++ { // Generating...

        f, _ := os.Create("h.txt") // creating...

        f.WriteString(string(i)) // writing...

        defer f.Close()
    }
}

Thanks!

Answer 1

There are a few issues with your code.

1) You're opening the file multiple times, every iteration of your loop; os.Create will truncate the file if it already exists, so you may be writing and truncating it on each iteration.

2) You're not checking that the file opens correctly without error

3) defer schedules code to run when the function ends, not at the end of the scope. (i.e. at the end of the iteration)

4) You should convert the integer properly, using a conversion and checking the error: _, err := f.WriteString(fmt.Sprintf("%d",i)), and then check the error.

Try this:

package main

import (
    "fmt"
    "os"
)

func main() {
    f, err := os.Create("h.txt") // creating...
    if err != nil {
        fmt.Printf("error creating file: %v", err)
        return
    }
    defer f.Close()
    for i := 0; i < 10; i++ { // Generating...
        _, err = f.WriteString(fmt.Sprintf("%d
", i)) // writing...
        if err != nil {
            fmt.Printf("error writing string: %v", err)
        }
    }
}