比较 char 文件描述符 c

Question

我需要比较文件描述符中的 2 个字符。

我的文件 sample.txt 包括 "first" 我的文件 sample2.txt 包括 "firbbbbbbst"

我需要 return "not similar"，但它总是 returns "similar" 并且从未真正将行读取到缓冲区。

int main(int argc, char **argv)
{
ssize_t ret_in, ret_out;
char buffer[BUF_SIZE];
char buffer2[BUF_SIZE];
int where=0;    
int fileDes1;
int fileDes2;

      fileDes1 = open("home/aviad/Desktop/comparing/in1/sample.txt", O_RDONLY);
      fileDes2 = open("home/aviad/Desktop/comparing/in2/sample2.txt", O_RDONLY);
      while((ret_in = fread (buffer, BUF_SIZE, 1, fileDes1)) > 0)
      {
          ret_out= fread (buffer, BUF_SIZE, 1, fileDes2);

          if (buffer[where] == buffer2[where])
          {
              printf("%c", buffer[where]);
              where++;
          }
          else {
              printf("nor similar\n");
              break;
          }
      }
      printf("similar\n");
      printf("%c", buffer[2]);   //garbage
      printf("%c", buffer2[2]);  //garbage
      return 0;
}

Answer 1

您可能需要这个：

免责声明：未经测试的代码可能无法运行甚至无法编译，但它至少应该给您一个想法。总之还有进步空间

int main(int argc, char **argv)
{
ssize_t ret_in, ret_out;
char buffer[BUF_SIZE];
char buffer2[BUF_SIZE];
int where=0;    
int fileDes1;
int fileDes2;
int notsimilar = 0;
int i = 0;

      fileDes1 = open("home/aviad/Desktop/comparing/in1/sample.txt", O_RDONLY);
      fileDes2 = open("home/aviad/Desktop/comparing/in2/sample2.txt", O_RDONLY);

      while((ret_in = fread (buffer, BUF_SIZE, 1, fileDes1)) > 0)
      {
        ret_out= fread (buffer, BUF_SIZE, 1, fileDes2);

        if (ret_out != ret_in)  // file sizes different -> not similar
        {
          notsimilar = 1;
          break;
        }
        else
        {
          for (i = 0; i < ret_out)
          {
            if (buffer[i] == buffer2[i])
            {
                printf("%c", buffer[i]);
                where++;
            }
            else
            {
                notsimilar = 1;
            }
          }
        }
      }

      if (notsimilar)
        printf("similar\n");
      else
        printf("similar\n");

      printf("%c", buffer[i]);
      printf("%c", buffer2[i]);
      return 0;
}

您还应该测试文件是否真的可以打开。您只是假设这两个文件都存在。

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