cs50恢复问题：文件无法打开

Question

我正在处理 pset4 cs50 的恢复分配，我想我已经完成了我的代码。但是当我运行它时，它说：文件无法打开。如果我尝试双击文件 'card.raw'，会弹出一个提示：“无法打开 card.raw：文件格式不受支持”。请帮我弄清楚我的问题。这是我的代码：

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

int main(int argc, char *argv[])
{
      FILE * pFile = NULL;
     unsigned char *buffer = malloc(512);
      char* filename = NULL;
      int filenumber = 0;
    //If user didn't print 2 items
    if(argc != 2)
    {
        printf("Usage: ./recover image\n");
        return 1;
    }
    //THE PROBLEM IS HERE!!!
    //if it can't open the file: error message
      if (!pFile)
    {
        fprintf(stderr, "File cannot be opened\n");
        return 2;
    }
    //Open the file
pFile = fopen(argv[1], "r");
int j=0; 
// checking the card by 512b chunks 

//loop
while (pFile)
{
  int i =0;
  i++;

//k=fread (buffer, 512, i, *file);
int k = fread(buffer, 512, i, pFile);
//if buffer [0]== 0xff // checking if it's the header. If yes - creating a new jpeg;
if (buffer[0] == 0xff && buffer[1] == 0xd8 && buffer[2] == 0xff && (buffer[3] & 0xf0) == 0xe0)
{
// if it's not the first file, we should close the last one
if (filename != NULL)
{
    fclose(pFile);
}
//sprintf
sprintf(filename, "%03i.jpg", 2);
//FILE = fopen (W) 
pFile = fopen(filename, "w");
// fwrite (buffer, 512, j, *file1)
fwrite (buffer, 512, j, pFile);
//j=j+1
j = j + 1;
}
// if k<512 - end of the loop
if (k < 512)
{
    return 0;
}
}
free(buffer);
}

请帮我理解。谢谢

Answer 1

您在尝试打开文件之前检查打开是否失败：

if (!pFile) { fprintf(stderr, "File cannot be opened\n"); return 2; } //Open the file pFile = fopen(argv[1], "r");

把测试前的fopen调上去看看是否成功:

//Open the file pFile = fopen(argv[1], "r"); if (!pFile) { fprintf(stderr, "File cannot be opened\n"); return 2; }

cs50恢复问题：文件无法打开

Cs50 recover problem: file can't be opened

c

file

recover

cs50