CS50恢复分段故障

问题描述

这是从pset4 CS50恢复.编译时没有错误.当我运行代码时，出现分段错误.我不明白到底是什么错误.我查找了与其他人发布的关于分割错误的问题有关的解决方案，但它们似乎并不能解决我的问题.

This is Recover from pset4 CS50. There is no error when I compile it. When I run the code I get segmentation fault. I do not understand what exactly is the mistake. I have looked up solutions related to questions on segmentation fault posted by others but they don't seem to solve my problem.

有人可以解释什么地方出了问题以及如何解决.

Can somebody explain whats wrong and how do I solve it.

#include <stdio.h>
#include <stdint.h>
typedef uint8_t BYTE;

int main(int argc, char *argv[])
{

if (argc != 2)
{
    printf("Usage: ./recover image\n");
    return 1;
}

FILE *inFile = fopen(argv[1], "r");
if(!inFile)
{
    printf("Could not open file!\n");
    return 1;
}

BYTE buffer[512];
FILE *outFile = NULL;
int imageNum = 0;
char fileName[8];

while (!feof(inFile))
{
     fread(buffer, 1, sizeof(buffer), inFile);
     if (buffer[0] == 0xff && buffer[1] == 0xd8 && buffer[2] == 0xff && (buffer[4] & 0xf0) == 0xef0)
     {
         if (imageNum > 0)
         {
            fclose(outFile);
         }
         imageNum++;
         sprintf(fileName, "%03i.jpg", imageNum);
         outFile = fopen(fileName, "w");
     }
    if (outFile != NULL)
    {
        fwrite(buffer, 1, sizeof(buffer), outFile);
    }
}
fclose(outFile);
fclose(inFile);
return 0;
}

推荐答案

我通过更改以下代码行找到了上述问题的解决方案

I found the solution to problem above by changing these lines of code

while (!feof(inFile))

到

while (fread(buffer, sizeof(buffer), 1, inFile))

和

fread(buffer, 1, sizeof(buffer), inFile);
fwrite(buffer, 1, sizeof(buffer), outFile);

到

fread(buffer, sizeof(buffer), 1, inFile);
fwrite(buffer, sizeof(buffer), 1, outFile);

主要问题还是我的if条件发生了改变

Also the main issue was in my if condition which I changed from

if (buffer[0] == 0xff && buffer[1] == 0xd8 && buffer[2] == 0xff && (buffer[4] & 0xf0) == 0xef0)

到

 if (buffer[0] == 0xff && buffer[1] == 0xd8 && buffer[2] == 0xff && (buffer[3] & 0xf0) == 0xe0)

最后更改

imageNum++;
sprintf(fileName, "%03i.jpg", imageNum);
outFile = fopen(fileName, "w");

到

sprintf(fileName, "%03i.jpg", imageNum);
outFile = fopen(fileName, "w");
imageNum++;

谢谢大家的建议和帮助.

Thank you all for your suggestions and help.

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