c-PSET4 RECOVERY无法正确恢复图像

Question

我已经开始研究PSET 4 RECOVERY。我的程序编译成功，它通过了前3次测试，没有问题，但出于我的爱，我似乎找不到问题。它只是不能正确地恢复照片，我已经尝试将ptr更改为char，反之亦然，但无济于事。

这是代码：

#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 filenamen");
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;

感谢提供的任何帮助

Answer 1

因此，您可以进行此检查，看看是否找到了新图像的开头。如果你找到了一个新的图像，你想打开它。但看看这个分支的末端。检查它是否是新图像的开始，然后检查是否需要关闭图像。然后你结束两个分支。每次循环运行时，您都会无条件地打开一个新映像。这里唯一的错误是大括号的位置。

//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