如何在临时 hexdump 程序的第二列中添加纯文本文件？答案

【问题标题】：How do I add a plaintext file in a second column in a makeshift hexdump program?如何在临时 hexdump 程序的第二列中添加纯文本文件？
【发布时间】：2020-08-02 12:13:59
【问题描述】：

我正在尝试用 C 重新创建一个 hexdump 程序。这就是我目前所拥有的

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
typedef unsigned char byte;
void openfile(FILE **fptr, char *fname)
{
    *fptr = fopen(fname, "r");
    if(fptr == NULL)
    {
        fprintf(stderr, "How dare you... \n");
        exit(-1);
    }
}
int readContents(FILE *fptr, int *filesize, byte *array)
{
        return (fread(array, 1, *filesize, fptr));  // read all bytes from the file
}

int printit(FILE **fptr, int *filesize, byte *array)
{
    byte sixteen[17];

    readContents(*fptr, filesize, array);

    int idx;
    for(idx = 0; idx <= *filesize; idx++)
    {
        if((idx%16)==0)
        {       
            printf("%08x ", idx);
        }

        if((idx%8)==0)
        {
            printf(" ");
        }

        printf("%02x ", array[idx]);

        if((idx+1)%16==0) 
        {
        printf("\n");
        }
    }

    for(idx = 0; idx <= *filesize; idx++)
    {
        if((idx%16)==0)
        printf("%c ", array[idx]);
    }


}

int main(int argc, char *argv[])
{
    char filename[30];

    if(argc > 1)
    {
        strcpy(filename, argv[1]);
    }
    else
    {
        printf("Please enter a filename: ");
        scanf(" %[^\n]s", filename);
    }

    FILE *ptr;
    openfile(&ptr, filename);

    fseek(ptr, 0, SEEK_END);
    int filelen = ftell(ptr);
    printf("Length of file is: %d\n", filelen);
    fseek(ptr, 0, SEEK_SET);

    byte *bytes = malloc(filelen);


    printit(&ptr, &filelen, bytes);

    printf("\n");
    free(bytes);
    fclose(ptr);
}

偏移位置和十六进制成功地出现在输出中，但我似乎无法弄清楚我应该如何在右侧添加一个包含文件内容明文的列

这是没有它的输出的样子

00000010  03 00 3e 00 01 00 00 00  70 09 00 00 00 00 00 00 
00000020  40 00 00 00 00 00 00 00  98 2b 00 00 00 00 00 00 
00000030  00 00 00 00 40 00 38 00  09 00 40 00 1d 00 1c 00 
00000040  06 00 00 00 04 00 00 00  40 00 00 00 00 00 00 00 
00000050  40 00 00 00 00 00 00 00  40 00 00 00 00 00 00 00 
00000060  f8 01 00 00 00 00 00 00  f8 01 00 00 00 00 00 00 
00000070  08 00 00 00 00 00 00 00  03 00 00 00 04 00 00 00 
00000080  38 02 00 00 00 00 00 00  38 02 00 00 00 00 00 00 
00000090  38 02 00 00 00 00 00 00  1c 00 00 00 00 00 00 00 
000000a0  1c 00 00 00 00 00 00 00  01 00 00 00 00 00 00 00 
000000b0  01 00 00 00 05 00 00 00  00 00 00 00 00 00 00 00 
000000c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00 
000000d0  38 0f 00 00 00 00 00 00  38 0f 00 00 00 00 00 00 
000000e0  00 00 20 00 00 00 00 00  01 00 00 00 06 00 00 00 
000000f0  50 1d 00 00 00 00 00 00  50 1d 20 00 00 00 00 00 
00000100  50 1d 20 00 00 00 00 00  c0 02 00 00 00 00 00 00 
00000110  e0 02 00 00 00 00 00 00  00 00 20 00 00 00 00 00 
00000120  02 00 00 00 06 00 00 00  60 1d 00 00 00 00 00 00 
00000130  60 1d 20 00 00 00 00 00  60 1d 20 00 00 00 00 00 
00000140  f0 01 00 00 00 00 00 00  f0 01 00 00 00 00 00 00 
00000150  08 00 00 00 00 00 00 00  04 00 00 00 04 00 00 00 
00000160  54 02 00 00 00 00 00 00  54 02 00 00 00 00 00 00 
00000170  54 02 00 00 00 00 00 00  44 00 00 00 00 00 00 00 
00000180  44 00 00 00 00 00 00 00  04 00 00 00 00 00 00 00 
00000190  50 e5 74 64 04 00 00 00  f0 0d 00 00 00 00 00 00 
000001a0  f0 0d 00 00 00 00 00 00  f0 0d 00 00 00 00 00 00 
000001b0  3c 00 00 00 00 00 00 00  3c 00 00 00 00 00 00 00 
000001c0  04 00 00 00 00 00 00 00  51 e5 74 64 06 00 00 00 
000001d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00

这是明文出现在末尾的地方

  @   @ � 8 8    8  P P �  ` � T T D P � <     R P �  d o G  G `      J   o   +   D   u   �      
                                                                                                                                                   �   h . e n a c o s i i i L . I C n e b      u P p  �   �       p   �   �   �   �   �   �   � � � � � � � � � � � � � � � � 1 � � H 9 � ] H ) H � ] �  � � U � � � � 5 � � H � U  � � � � � � H ,  � � � � H � �  � �  � d � A   � � L  A �  n : D . V   x   f F d f  � X �       � 
                                                                                                                                            �  �  � A                                                                                                                                                                                                                                    p  
     �                                                                         

              � � � � �      `  � � � �  6 V    G . 4   8   t   �   �   0   X   `      �   P   `         �   0 7  X m  P �   �   �  ` �  � �      K   g   �   �   �   �      '    C e 0 � +  f  z w   �   �   �  X  f m o o d a n  n e A _ M _ F L _ p . a . e r 5 @ t L G b L a @ l _ _ s c @ b o 5 @ @ T e b I f 2 I a r t . n . s n e l n r m f m c      8    T    t    �    �    �    �    �    0   B    X    p    `   p             �    0    P   X   `    P          0     @    x    �

我也碰巧在读一个 ELF 文件，仅供参考

编辑：我忘了粘贴#include stdio.h

【问题讨论】：

贴出的代码无法编译！该代码使用的函数如下：printf() 和 fopen() 和 fclose() 和 fread() 以及定义的项目，如 FILE* 和 NULL。要使用这些项目，代码需要以下语句：#include <stdio.h>
函数：fread() 返回一个size_t，而不是int，而函数：printit() 忽略了函数的返回值：readContents() 为什么是函数：@ 987654336@ 在不修改该指针时被传递FILE **？
您输出 16 位十六进制值，当您完成输出最后一个十六进制值时，然后打印一个可选的分隔符，例如" | "，然后循环遍历这 16 个字节中的每一个输出可打印值 if (isprint())，否则输出 ' '，然后为该输出行打印 '\n'。
关于：for(idx = 0; idx <= *filesize; idx++) { if((idx%16)==0) printf("%c ", array[idx]); } 这只会输出一个字符。注意<= 将执行一个太多的循环。建议：<。建议：for(idx = 0; idx % 16; idx++) { if( isprint( array[idx] ) { printf("%c ", array[idx]); } else { printf( "%c ", '.' ); } }
关于错误信息：fprintf(stderr, "How dare you... \n"); 当错误来自 C 库函数时，应将您的错误信息和系统认为发生错误的文本原因输出到stderr。建议：perror( "How dare you..." ); 处理这两个动作。此外，“你怎么敢……”告诉用户没有任何用处。建议：perror( "fopen failed" );

标签： c hexdump

【解决方案1】：

（编辑以匹配hexdump -Cv输出）

按照相同的思路并继续我的评论，如果您以 16 字节块的形式从输入文件中读取，您可以输出地址和十六进制字节，然后添加分隔符，然后在字节上再次单独循环以提供 ASCII 值作为右列。下面的程序将要读取的文件名作为第一个参数（如果没有给出参数，则默认从stdin 读取）。

如果提供了文件名，您还可以提供第二个选项，该选项提供用于代替 ASCII 输出中的非打印字符的字符（您实际上应该实现 getopt 来处理参数 - 但如果留下如果你愿意的话给你）。

一个快速的实现可能是：

#include <stdio.h>

#define OFFSET 16   /* bytes to display per-line of output */

int main (int argc, char const *argv[])
{
    char buff[OFFSET] = "",
        sep = argc > 2 ? *argv[2] : '.';    /* default non-print char ','  */
    int bytes,                              /* (add getopt to handle opts) */
        address = 0,
        i;

    /* read from filename provided as 1st argument (stdin by default) */
    FILE *fp = argc > 1 ? fopen (argv[1], "rb") : stdin;
    if (!fp) {  /* validate file open for reading */
        perror ("fopen");
        return 1;
    }

    /* read OFFSET number of bytes at a time */
    while ((bytes = fread(buff, 1, sizeof buff, fp)) > 0) {
        /* print address */
        printf("%0*x  ", OFFSET / 2, address);
        address += OFFSET;

        /* print hex values */
        for (i = 0; i < OFFSET; i++) {
            if (i && i % (OFFSET / 2) == 0) /* additional space between bytes */
                putchar (' ');
            if (i >= bytes)                 /* final line where i >= bytes */
                fputs ("   ", stdout);
            else    /* output zero-padded hex-byte */
                printf("%02hhx ", (unsigned char)buff[i]);
        }
        fputs (" |", stdout);               /* add separator */

        /* print ascii values - putchar() outputs a single char */
        for (i = 0; i < bytes; i++)
            putchar (buff[i] >= ' ' && buff[i] <= '~' ? buff[i] : sep);
        puts ("|");     /* add closing '|' and \n */
    }
    printf("%0*x\n", OFFSET / 2, address);  /* output final address */

    if (fp != stdin)    /* close file if not stdin */
        fclose (fp);
}

使用/输出示例

$ ./bin/hexdump dat/animals.bin.dat
00000000  01 00 41 62 69 67 61 69  6c 00 00 00 04 00 00 00  |..Abigail.......|
00000010  74 01 00 00 74 01 43 61  70 72 69 63 6f 72 6e 69  |t...t.Capricorni|
00000020  73 20 73 75 6d 61 74 72  61 65 6e 73 69 73 00 00  |s sumatraensis..|
00000030  5c 3f 1b 00 5c 4f 1b 00  5c 53 08 00 02 00 75 6e  |\?..\O..\S....un|
00000040  6b 6e 6f 77 6e 00 00 00  04 00 00 00 74 01 00 00  |known.......t...|
...
00000370  73 00 73 69 73 00 00 00  5c 3f 1b 00 5c 4f 1b 00  |s.sis...\?..\O..|
00000380  5c 58 01 00                                       |\X..|
00000384

在第二个参数中提供一个空格作为 ASCII 输出的非打印字符：

$ ./bin/hexdump dat/animals.bin.dat ' '
00000000  01 00 41 62 69 67 61 69  6c 00 00 00 04 00 00 00  |  Abigail       |
00000010  74 01 00 00 74 01 43 61  70 72 69 63 6f 72 6e 69  |t   t Capricorni|
00000020  73 20 73 75 6d 61 74 72  61 65 6e 73 69 73 00 00  |s sumatraensis  |
00000030  5c 3f 1b 00 5c 4f 1b 00  5c 53 08 00 02 00 75 6e  |\?  \O  \S    un|
00000040  6b 6e 6f 77 6e 00 00 00  04 00 00 00 74 01 00 00  |known       t   |
...
00000370  73 00 73 69 73 00 00 00  5c 3f 1b 00 5c 4f 1b 00  |s sis   \?  \O  |
00000380  5c 58 01 00                                       |\X  |
00000384

与hexdump -Cv比较：

$ hexdump -Cv dat/animals.bin.dat
00000000  01 00 41 62 69 67 61 69  6c 00 00 00 04 00 00 00  |..Abigail.......|
00000010  74 01 00 00 74 01 43 61  70 72 69 63 6f 72 6e 69  |t...t.Capricorni|
00000020  73 20 73 75 6d 61 74 72  61 65 6e 73 69 73 00 00  |s sumatraensis..|
00000030  5c 3f 1b 00 5c 4f 1b 00  5c 53 08 00 02 00 75 6e  |\?..\O..\S....un|
00000040  6b 6e 6f 77 6e 00 00 00  04 00 00 00 74 01 00 00  |known.......t...|
...
00000370  73 00 73 69 73 00 00 00  5c 3f 1b 00 5c 4f 1b 00  |s.sis...\?..\O..|
00000380  5c 58 01 00                                       |\X..|
00000384

如果您还有其他问题，请告诉我。

【讨论】：

【解决方案2】：

以下建议的代码：

干净编译
检查并处理任何错误
产生所需的输出
避免使用malloc() 和free()
不会尝试一次性消耗整个输入文件

现在，建议的代码：

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


#define MAX_BYTES 16
#define MAX_FILENAME_LEN 30

typedef unsigned char byte;

static unsigned int idx = 0;

void printit( size_t bytesRead, byte *array)
{
    // display index into file
    printf("\n%08x ", idx);

    for( size_t i = 0; i < bytesRead; i++  )
    {
        if( i == 8 )
        {
            printf(" ");
        }

        printf("%02x ", array[i]);
    }

    printf( "%s", " | " );

    for( size_t i = 0; i< bytesRead; i++ )
    {
        if( isalpha( array[i] ) )
        {
             printf( "%c", array[i] );
        }

        else
        {
             printf( "%c", '.' );
        }
    }
    printf( "%s", " | " );

    idx += (unsigned int)bytesRead;  
}


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

    if(argc > 1)
    {
        strncpy(filename, argv[1], MAX_FILENAME_LEN );
    }

    else
    {
        printf("Please enter a filename: ");
        if( scanf("%29s", filename) != 1 )
        {
            fprintf( stderr, "scanf to get filename from user failed\n" );
            exit( EXIT_FAILURE );
        }
    }

    FILE *fp = fopen(filename, "rb");
    if( ! fp )
    {
        perror( "fopen for input file failed");
        exit( EXIT_FAILURE );
    }

    fseek( fp, 0, SEEK_END );
    long filelen = ftell( fp );
    printf("Length of file is: %ld\n", filelen);
    fseek( fp, 0, SEEK_SET );

    byte filedata[ 16 ];
    size_t bytesRead;
    while( ( bytesRead = fread( filedata, 1, sizeof filedata, fp )) > 0 )
    {
        //printf( "bytesRead: %zu\n", bytesRead );
        printit( bytesRead, filedata );
    }

    fclose( fp );
}

这是针对源文件的建议代码的典型运行：

Please enter a filename: untitled2.c
Length of file is: 1533

00000000 09 23 69 6e 63 6c 75 64  65 20 3c 73 74 72 69 6e  | ..include..strin | 
00000010 67 2e 68 3e 0a 09 23 69  6e 63 6c 75 64 65 20 3c  | g.h....include.. | 
00000020 73 74 64 6c 69 62 2e 68  3e 0a 09 23 69 6e 63 6c  | stdlib.h....incl | 
00000030 75 64 65 20 3c 73 74 64  69 6f 2e 68 3e 0a 09 23  | ude..stdio.h.... | 
00000040 69 6e 63 6c 75 64 65 20  3c 63 74 79 70 65 2e 68  | include..ctype.h | 
00000050 3e 0a 0a 0a 09 23 64 65  66 69 6e 65 20 4d 41 58  | ......define.MAX | 
00000060 5f 42 59 54 45 53 20 31  36 0a 09 23 64 65 66 69  | .BYTES......defi | 
00000070 6e 65 20 4d 41 58 5f 46  49 4c 45 4e 41 4d 45 5f  | ne.MAX.FILENAME. | 
00000080 4c 45 4e 20 33 30 0a 0a  09 74 79 70 65 64 65 66  | LEN......typedef | 
00000090 20 75 6e 73 69 67 6e 65  64 20 63 68 61 72 20 62  | .unsigned.char.b | 
000000a0 79 74 65 3b 0a 0a 09 73  74 61 74 69 63 20 75 6e  | yte....static.un | 
000000b0 73 69 67 6e 65 64 20 69  6e 74 20 69 64 78 20 3d  | signed.int.idx.. | 
000000c0 20 30 3b 0a 0a 09 76 6f  69 64 20 70 72 69 6e 74  | ......void.print | 
000000d0 69 74 28 20 73 69 7a 65  5f 74 20 62 79 74 65 73  | it..size.t.bytes | 
000000e0 52 65 61 64 2c 20 62 79  74 65 20 2a 61 72 72 61  | Read..byte..arra | 
000000f0 79 29 0a 09 7b 0a 09 09  2f 2f 20 64 69 73 70 6c  | y..........displ | 
00000100 61 79 20 69 6e 64 65 78  20 69 6e 74 6f 20 66 69  | ay.index.into.fi | 
00000110 6c 65 0a 09 09 70 72 69  6e 74 66 28 22 5c 6e 25  | le...printf...n. | 
00000120 30 38 78 20 22 2c 20 69  64 78 29 3b 0a 09 09 0a  | ..x....idx...... | 
00000130 09 09 66 6f 72 28 20 73  69 7a 65 5f 74 20 69 20  | ..for..size.t.i. | 
00000140 3d 20 30 3b 20 69 20 3c  20 62 79 74 65 73 52 65  | .....i...bytesRe | 
00000150 61 64 3b 20 69 2b 2b 20  20 29 0a 09 09 7b 0a 09  | ad..i........... | 
00000160 09 09 69 66 28 20 69 20  3d 3d 20 38 20 29 0a 09  | ..if..i......... | 
00000170 09 09 7b 0a 09 09 09 09  70 72 69 6e 74 66 28 22  | ........printf.. | 
00000180 20 22 29 3b 0a 09 09 09  7d 0a 0a 09 09 09 70 72  | ..............pr | 
00000190 69 6e 74 66 28 22 25 30  32 78 20 22 2c 20 61 72  | intf.....x....ar | 
000001a0 72 61 79 5b 69 5d 29 3b  0a 09 09 7d 0a 09 09 0a  | ray.i........... | 
000001b0 09 09 70 72 69 6e 74 66  28 20 22 25 73 22 2c 20  | ..printf....s... | 
000001c0 22 20 7c 20 22 20 29 3b  0a 09 09 0a 09 09 66 6f  | ..............fo | 
000001d0 72 28 20 73 69 7a 65 5f  74 20 69 20 3d 20 30 3b  | r..size.t.i..... | 
000001e0 20 69 3c 20 62 79 74 65  73 52 65 61 64 3b 20 69  | .i..bytesRead..i | 
000001f0 2b 2b 20 29 0a 09 09 7b  0a 09 09 09 69 66 28 20  | ............if.. | 
00000200 69 73 61 6c 70 68 61 28  20 61 72 72 61 79 5b 69  | isalpha..array.i | 
00000210 5d 20 29 20 29 0a 09 09  09 7b 0a 09 09 09 09 20  | ................ | 
00000220 70 72 69 6e 74 66 28 20  22 25 63 22 2c 20 61 72  | printf....c...ar | 
00000230 72 61 79 5b 69 5d 20 29  3b 0a 09 09 09 7d 0a 09  | ray.i........... | 
00000240 09 09 20 0a 09 09 09 65  6c 73 65 0a 09 09 09 7b  | .......else..... | 
00000250 0a 09 09 09 09 20 70 72  69 6e 74 66 28 20 22 25  | ......printf.... | 
00000260 63 22 2c 20 27 2e 27 20  29 3b 0a 09 09 09 7d 0a  | c............... | 
00000270 09 09 7d 0a 09 09 70 72  69 6e 74 66 28 20 22 25  | ......printf.... | 
00000280 73 22 2c 20 22 20 7c 20  22 20 29 3b 0a 09 09 0a  | s............... | 
00000290 09 09 69 64 78 20 2b 3d  20 28 75 6e 73 69 67 6e  | ..idx.....unsign | 
000002a0 65 64 20 69 6e 74 29 62  79 74 65 73 52 65 61 64  | ed.int.bytesRead | 
000002b0 3b 20 20 0a 09 7d 0a 0a  0a 09 69 6e 74 20 6d 61  | ..........int.ma | 
000002c0 69 6e 28 69 6e 74 20 61  72 67 63 2c 20 63 68 61  | in.int.argc..cha | 
000002d0 72 20 2a 61 72 67 76 5b  5d 29 0a 09 7b 0a 09 09  | r..argv......... | 
000002e0 63 68 61 72 20 66 69 6c  65 6e 61 6d 65 5b 20 4d  | char.filename..M | 
000002f0 41 58 5f 46 49 4c 45 4e  41 4d 45 5f 4c 45 4e 20  | AX.FILENAME.LEN. | 
00000300 5d 3b 0a 0a 09 09 69 66  28 61 72 67 63 20 3e 20  | ......if.argc... | 
00000310 31 29 0a 09 09 7b 0a 09  09 09 73 74 72 6e 63 70  | ..........strncp | 
00000320 79 28 66 69 6c 65 6e 61  6d 65 2c 20 61 72 67 76  | y.filename..argv | 
00000330 5b 31 5d 2c 20 4d 41 58  5f 46 49 4c 45 4e 41 4d  | .....MAX.FILENAM | 
00000340 45 5f 4c 45 4e 20 29 3b  0a 09 09 7d 0a 09 09 0a  | E.LEN........... | 
00000350 09 09 65 6c 73 65 0a 09  09 7b 0a 09 09 09 70 72  | ..else........pr | 
00000360 69 6e 74 66 28 22 50 6c  65 61 73 65 20 65 6e 74  | intf..Please.ent | 
00000370 65 72 20 61 20 66 69 6c  65 6e 61 6d 65 3a 20 22  | er.a.filename... | 
00000380 29 3b 0a 09 09 09 69 66  28 20 73 63 61 6e 66 28  | ......if..scanf. | 
00000390 22 25 32 39 73 22 2c 20  66 69 6c 65 6e 61 6d 65  | ....s...filename | 
000003a0 29 20 21 3d 20 31 20 29  0a 09 09 09 7b 0a 09 09  | ................ | 
000003b0 09 09 66 70 72 69 6e 74  66 28 20 73 74 64 65 72  | ..fprintf..stder | 
000003c0 72 2c 20 22 73 63 61 6e  66 20 74 6f 20 67 65 74  | r...scanf.to.get | 
000003d0 20 66 69 6c 65 6e 61 6d  65 20 66 72 6f 6d 20 75  | .filename.from.u | 
000003e0 73 65 72 20 66 61 69 6c  65 64 5c 6e 22 20 29 3b  | ser.failed.n.... | 
000003f0 0a 09 09 09 09 65 78 69  74 28 20 45 58 49 54 5f  | .....exit..EXIT. | 
00000400 46 41 49 4c 55 52 45 20  29 3b 0a 09 09 09 7d 0a  | FAILURE......... | 
00000410 09 09 7d 0a 0a 09 09 46  49 4c 45 20 2a 66 70 20  | .......FILE..fp. | 
00000420 3d 20 66 6f 70 65 6e 28  66 69 6c 65 6e 61 6d 65  | ..fopen.filename | 
00000430 2c 20 22 72 62 22 29 3b  0a 09 09 69 66 28 20 21  | ...rb......if... | 
00000440 20 66 70 20 29 0a 09 09  7b 0a 09 09 09 70 65 72  | .fp..........per | 
00000450 72 6f 72 28 20 22 66 6f  70 65 6e 20 66 6f 72 20  | ror...fopen.for. | 
00000460 69 6e 70 75 74 20 66 69  6c 65 20 66 61 69 6c 65  | input.file.faile | 
00000470 64 22 29 3b 0a 09 09 09  65 78 69 74 28 20 45 58  | d.......exit..EX | 
00000480 49 54 5f 46 41 49 4c 55  52 45 20 29 3b 0a 09 09  | IT.FAILURE...... | 
00000490 7d 0a 0a 09 09 66 73 65  65 6b 28 20 66 70 2c 20  | .....fseek..fp.. | 
000004a0 30 2c 20 53 45 45 4b 5f  45 4e 44 20 29 3b 0a 09  | ...SEEK.END..... | 
000004b0 09 6c 6f 6e 67 20 66 69  6c 65 6c 65 6e 20 3d 20  | .long.filelen... | 
000004c0 66 74 65 6c 6c 28 20 66  70 20 29 3b 0a 09 09 70  | ftell..fp......p | 
000004d0 72 69 6e 74 66 28 22 4c  65 6e 67 74 68 20 6f 66  | rintf..Length.of | 
000004e0 20 66 69 6c 65 20 69 73  3a 20 25 6c 64 5c 6e 22  | .file.is...ld.n. | 
000004f0 2c 20 66 69 6c 65 6c 65  6e 29 3b 0a 09 09 66 73  | ..filelen.....fs | 
00000500 65 65 6b 28 20 66 70 2c  20 30 2c 20 53 45 45 4b  | eek..fp.....SEEK | 
00000510 5f 53 45 54 20 29 3b 0a  09 09 0a 09 09 62 79 74  | .SET.........byt | 
00000520 65 20 66 69 6c 65 64 61  74 61 5b 20 31 36 20 5d  | e.filedata...... | 
00000530 3b 0a 09 09 73 69 7a 65  5f 74 20 62 79 74 65 73  | ....size.t.bytes | 
00000540 52 65 61 64 3b 0a 09 09  77 68 69 6c 65 28 20 28  | Read....while... | 
00000550 20 62 79 74 65 73 52 65  61 64 20 3d 20 66 72 65  | .bytesRead...fre | 
00000560 61 64 28 20 66 69 6c 65  64 61 74 61 2c 20 31 2c  | ad..filedata.... | 
00000570 20 73 69 7a 65 6f 66 20  66 69 6c 65 64 61 74 61  | .sizeof.filedata | 
00000580 2c 20 66 70 20 29 29 20  3e 20 30 20 29 0a 09 09  | ..fp............ | 
00000590 7b 0a 09 09 09 2f 2f 70  72 69 6e 74 66 28 20 22  | .......printf... | 
000005a0 62 79 74 65 73 52 65 61  64 3a 20 25 7a 75 5c 6e  | bytesRead...zu.n | 
000005b0 22 2c 20 62 79 74 65 73  52 65 61 64 20 29 3b 0a  | ...bytesRead.... | 
000005c0 09 09 09 70 72 69 6e 74  69 74 28 20 62 79 74 65  | ...printit..byte | 
000005d0 73 52 65 61 64 2c 20 66  69 6c 65 64 61 74 61 20  | sRead..filedata. | 
000005e0 29 3b 0a 09 09 7d 0a 09  09 0a 09 09 66 63 6c 6f  | ............fclo | 
000005f0 73 65 28 20 66 70 20 29  3b 0a 09 7d 0a  | se..fp....... |

注意：当最终读取小于 16 字节时，您可能需要用空格填写输入的最后一行

请注意，您可能需要将 if( isalpha() ) 修改为 if( isprint() )，以便打印字母 a..z 和 A..Z 以外的内容

【讨论】：

将printit() 中的第一个循环更改为for( size_t i = 0; i < MAX_BYTES; i++ ) 以修复最后一行输出，但做得很好。在您在main() 中调用printit( bytesRead, filedata ); 后，还要memset (filedata, 0, MAX_BYTES);，以确保在最后一行发生短读取时最终字节为零。
@DavidC.Rankin，我试图让 OP 去做一些需要 OP 完全理解答案的事情，以便他们可以修复输出的最后一行
这也是一个很好的方法——有一点刻意的学习……

【解决方案3】：

我对这份工作的态度会有所不同。事实上，（多年前）我的工作方式有所不同：

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

int main(int argc, char **argv) {
    unsigned long offset = 0;
    FILE *input;
    int bytes, i, j;
    unsigned char buffer[16];
    char outbuffer[60];

    if ( argc < 2 ) {
        fprintf(stderr, "\nUsage: dump filename [filename...]");
        return EXIT_FAILURE;
    }

    for (j=1;j<argc; ++j) {

        if ( NULL ==(input=fopen(argv[j], "rb")))
            continue;

        printf("\n%s:\n", argv[j]);

        while (0 < (bytes=fread(buffer, 1, 16, input))) {
            sprintf(outbuffer, "%8.8lx: ", offset+=16);
            for (i=0;i<bytes;i++) {
                sprintf(outbuffer+10+3*i, "%2.2X ",buffer[i]);
                if (!isprint(buffer[i]))
                    buffer[i] = '.';
            }
            printf("%-60s %*.*s\n", outbuffer, bytes, bytes, buffer);
        }
        fclose(input);
    }
    return 0;
}

【讨论】：