二进制翻译

发布于 2024-11-02 05:13:25 字数 301 浏览 3 评论 0原文

#include <stdio.h>

int main() {
  unsigned char data[1];

  FILE *f = fopen("bill.jpg", "rb");

  while (!feof(f)) {
    if (fread(data, 1, 1, f) > 0) {
      printf("0x%02x\n", data[0]);
    }
  }
  fclose(f);
}

这是正确的吗？我很担心，因为如果我使用 hexdump 查看文件，我会得到完全不同的输出。

原文

#include <stdio.h>

int main() {
  unsigned char data[1];

  FILE *f = fopen("bill.jpg", "rb");

  while (!feof(f)) {
    if (fread(data, 1, 1, f) > 0) {
      printf("0x%02x\n", data[0]);
    }
  }
  fclose(f);
}

Is this the right? I am worried because if I view the file using hexdump, I get completely different output.

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葮薆情 2024-11-09 05:13:25

这应该以十六进制正确打印文件的第一个字节。

检查所使用的 Hexdump 实用程序的文档，或告诉我们正在使用哪个平台。一些转储实用程序在每行上以相反的顺序显示字节，以使小端读取更加直观 - 一旦您了解了它在做什么。

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Spring初心 2024-11-09 05:13:25

抱歉，但不 - while (!feof(f)) 本质上总是错误的 - 它通常会读取文件中的最后一项两次。这是我几年前写的一个相当可用的六角转储器：

/* public domain by Jerry Coffin, tested with MS C 10.0 and BC 4.5
 */
#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;
}

I'm sorry, but no -- while (!feof(f)) is essentially always wrong -- it'll typically appear to read the last item in the file twice. Here's a reasonably usable hex dumper I wrote a few years ago:

/* public domain by Jerry Coffin, tested with MS C 10.0 and BC 4.5
 */
#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;
}

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