Go语言中正确生成PGM文件：避免二进制输出的陷阱

package main

import (
    "bufio"
    "fmt"
    "os"
    "strconv" // 导入strconv包

    // 假设 img 是一个 [][]int 类型的图像数据
    // img := make([][]int, height)
    // for i := range img {
    //     img[i] = make([]int, width)
    // }
)

func main() {
    filename := "output.pgm"
    width := 100
    height := 50
    maxVal := 255

    fd, err := os.Create(filename)
    if err != nil {
        fmt.Printf("Error creating file: %v\n", err)
        return
    }
    defer fd.Close()

    wr := bufio.NewWriter(fd)

    // 错误的字符串转换方式
    // str := "P2\n" + filename + "\n" + string(width) + " " + string(height) + "\n" + string(maxVal) + "\n"
    // if _, err := wr.WriteString(str); err != nil {
    //  fmt.Printf("Error writing header: %v\n", err)
    //  return
    // }

    // ... 循环写入像素数据 ...

    // wr.Flush() // 不要忘记刷新缓冲区
}

package main

import (
    "bufio"
    "fmt"
    "os"
    "strconv" // 导入strconv包
)

func main() {
    filename := "output.pgm"
    width := 100
    height := 50
    maxVal := 255

    // 模拟图像数据 (这里只是一个占位符，实际应为处理后的图像数据)
    img := make([][]int, height)
    for i := range img {
        img[i] = make([]int, width)
        for j := range img[i] {
            img[i][j] = (i + j) % (maxVal + 1) // 示例像素值
        }
    }

    fd, err := os.Create(filename)
    if err != nil {
        fmt.Printf("Error creating file: %v\n", err)
        return
    }
    defer fd.Close()

    wr := bufio.NewWriter(fd)

    // 正确的字符串转换方式：使用 strconv.Itoa()
    header := "P2\n" +
        strconv.Itoa(width) + " " + strconv.Itoa(height) + "\n" +
        strconv.Itoa(maxVal) + "\n"

    if _, err := wr.WriteString(header); err != nil {
        fmt.Printf("Error writing header: %v\n", err)
        return
    }

    // 循环写入像素数据
    for i := 0; i < height; i++ {
        for j := 0; j < width; j++ {
            if _, err := wr.WriteString(strconv.Itoa(img[i][j])); err != nil {
                fmt.Printf("Error writing pixel: %v\n", err)
                return
            }
            if j < width-1 {
                if _, err := wr.WriteString(" "); err != nil { // 像素之间用空格分隔
                    fmt.Printf("Error writing space: %v\n", err)
                    return
                }
            }
        }
        if _, err := wr.WriteString("\n"); err != nil { // 每行像素后换行
            fmt.Printf("Error writing newline: %v\n", err)
            return
        }
    }

    // 刷新缓冲区，确保所有数据都写入文件
    if err := wr.Flush(); err != nil {
        fmt.Printf("Error flushing writer: %v\n", err)
        return
    }

    fmt.Printf("PGM file '%s' created successfully.\n", filename)
}