PSET4 RECOVERY 无法正确恢复图像

Question

我已经开始研究 PSET 4 恢复。我的程序编译成功，前 3 次测试没问题，但看在我的份上，我似乎找不到问题所在。它只是不能正确恢复照片，我尝试将 ptr 更改为 char，反之亦然，但无济于事。

代码如下：

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

typedef uint8_t BYTE;
int main(int argc, char *argv[])
{
    //check for number of arguments
    if (argc != 2)
    {
        printf("Usage: ./recover filename\n");
        return 1;
    }
    //initialize files
    char *input_name = argv[1];
    FILE *input = fopen(input_name, "r");
    if (input == NULL)
    {
        //check if file is openable
        printf("File %s could not be opened!", input_name);
        return 1;
    }
    //initialize files and pointers
    BYTE file[512];
    int counter = 0;
    FILE *img = NULL;
    char img_name[8];
    //loop as long as files returns bytes
    while(fread(&file, 512, 1, input) == 1)
    {
        //check if file is jpeg
        if (file[0] == 0xff && file[1] == 0xd8 && file[2] == 0xff && (file[3] & 0xf0) == 0xe0)
        {
            //if a previous file is open, close it
            if (counter != 0)
            fclose(img);
        }
        //initialize new file
        sprintf(img_name, "%03i.jpg", counter);
        img = fopen(img_name, "w");
        counter++;
        //if jpeg is found, write
        if (counter != 0)
        {
            fwrite(&file, 512, 1, img);
        }
    }
        fclose(input);
        fclose(img);
        return 0;

感谢任何帮助

Answer 1

因此，您已进行此检查以查看是否找到了新图像的开头。如果你找到一张新图片，你想打开它。但是看看那个分支结束的地方。您检查它是否是新图像的开始，然后检查图像是否需要关闭。然后你结束两个分支。每次循环运行时，您无条件地打开一个新图像。整个错误是花括号的位置。

//check if file is jpeg
if (file[0] == 0xff && file[1] == 0xd8 && file[2] == 0xff && (file[3] & 0xf0) == 0xe0)
{
    //if a previous file is open, close it
    if (counter != 0)
    fclose(img);
} // <- !! what !!
//initialize new file
sprintf(img_name, "%03i.jpg", counter);
img = fopen(img_name, "w");
counter++;
//if jpeg is found, write

PSET4 RECOVERY 无法正确恢复图像

PSET4 RECOVERY does not recover images correctly

c

data-recovery

cs50