Question

所以我试图读取每个块有4个字节的二进制文件，当我在我的文件上执行hexdump时输出： 0000000 0022 0000 6261 6463 3030 3030 6261 6463 0000010 3030 3030 6261 6463 3030 3030 6261 6463 * 00000d0 3030 3030 6261 6463 3030 3030 000a 00000dd （每行数字之间不应该有一行，抱歉）

但是当它将这些值读入数组时，这是我得到的输出：

34 61000000 30646362 61303030 30646362 61303030 30646362 61303030 30646362 2283030 0 44c5bbc0 7fff 22 0 14fea515 7f68 0 0 22 0 22 0 4007b2 0 1 0 1000 0 2289010 0 44c5bbc0 7f

我在网上遵循了很多说明，我真的不确定从哪里开始。

以下是我正在使用的代码：

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
int main(int argc, char** argv)
{
    unsigned char buffer[1];
    FILE *filePointer;
    filePointer = fopen(argv[1], "rb");

    //unsigned char buffer[filePointer];

    int readVal = 0;

    readVal = fread(buffer, sizeof(buffer), 1, filePointer);
    if (readVal == 0)
    {
            printf("File did not read anything\n");
    }

    int size = buffer[0];

    /*int i = 1;    

    for(; i < 1; i++)
    {
            printf("%x ", buffer[i]);
    }

    */
    //int size = buffer[0];
    printf("%d\n", size);
    unsigned int array[size];
    int otherDataElements;

    otherDataElements = fread(array, sizeof(buffer), size, filePointer);

    if (otherDataElements == 0)
    {
            printf("There was nothing there!");
    }

    int j = 0;
    for (; j < size; j++)
    {
            printf("%x ", array[j]);
    }
    return 0;
}

有一些代码被注释掉了，忽略它。谢谢！

Answer 1

什么是size？字节数？还是整数？

这似乎很可疑：

otherDataElements = fread(array, sizeof(buffer), size, filePointer);

尝试更改为：

otherDataElements = fread(array, sizeof(unsigned int), size/sizeof(unsigned int), filePointer);

因为数组是无符号整数的array，而fread的第二个参数会询问您要读取的每个元素的大小。如果你想将文件内容解释为我认为的4字节整数数组，文件长度也应该是4的倍数。

无论如何，我的机器上的这个程序的输出是（这是类似的程序，因为你刚刚添加了将数据写入文件进行测试 - 我已经简化了阅读）：

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

void test()
{
    unsigned char buffer[1];
    FILE *filePointer;
    filePointer = fopen("/Users/macbookair/Documents/test/test/t.bin", "rb");

    //unsigned char buffer[filePointer];


    //readVal = fread(buffer, sizeof(buffer), 1, filePointer);
    //if (readVal == 0)
    //{
    //     printf("File did not read anything\n");
    // }

    //int size = 4;

    /*int i = 1;

     for(; i < 1; i++)
     {
     printf("%x ", buffer[i]);
     }

     */
    //int size = buffer[0];
    //printf("%d\n", size);
    unsigned int array[4] = {0};
    int otherDataElements;
    int nrOfInts = 1; // In this test method we only want to read 1 integer from file, we assume there is one integer only

    otherDataElements = fread(array, sizeof(unsigned int), nrOfInts, filePointer);

    if (otherDataElements == 0)
    {
        printf("There was nothing there!");
    }

    int j = 0;
    for (; j < nrOfInts; j++)
    {
        printf("%x ", array[j]);
    }
}


int main(int argc, const char * argv[])
{
    // Just do a test write to file. Write 4 bytes to read back later.
    FILE *write_ptr;
    unsigned char buffer[4] = {0,1,2,3};
    write_ptr = fopen("/Users/macbookair/Documents/test/test/t.bin","wb");   

    fwrite(buffer,sizeof(buffer),1,write_ptr);  
    fclose(write_ptr);

    // Call our method for reading the data
    test();
    return 0;
}

这样：

你可以看到输出是交换的，但这是因为字节顺序 - 当我的计算机将字节00 01 02 03解释为整数的字节时，它以小端方式这样做 - 因此输出是整数03020100.你可能想要在你的情况下也考虑这一点。所以在我的情况下，我认为它工作正常。

读取C中的二进制文件，然后将文件中的数据与我读过的内容进行匹配

1 个答案: