PHP (ZLIB) 解压 C (ZLIB) 压缩数组会返回乱码

发布于 2025-01-03 15:24:39 字数 1896 浏览 1 评论 0原文

我有一组存储在数据库中的 ZLIB 压缩/base64 编码字符串（在 C 程序中完成）。我编写了一个小型 PHP 页面，应该检索这些值并绘制它们（字符串最初是浮点数列表）。

压缩/编码的 C 程序块：（

error=compress2(comp_buffer, &comp_length,(const Bytef*)data.mz ,(uLongf)length,Z_DEFAULT_COMPRESSION); /* compression */
if (error != Z_OK) {fprintf(stderr,"zlib error..exiting"); exit(EXIT_FAILURE);}
mz_binary=g_base64_encode (comp_buffer,comp_length); /* encoding */

示例）原始输入格式：

292.1149    8379.5928
366.1519  101313.3906
367.3778   20361.8105
369.1290   17033.3223
375.4355    1159.1841
467.3191    8445.3926

每一列都被压缩/编码为单个字符串。为了重建原始数据，我使用以下代码：

//$row[4] is retrieved from the DB and contains the compressed/encoded string
$mz = base64_decode($row[4]);
$unc_mz = gzuncompress($mz);
echo $unc_mz;

但这给了我以下输出：

f6jEÍ„]EšiSE@IEfŽ

任何人都可以给我一个关于我可能缺少什么的提示/提示吗？

------ 添加信息 -----

我觉得问题来自于当前 php 将 $unc_mz 视为单个字符串的事实，而实际上我必须重新构造一个包含 X 行的数组（此输出来自 9 行文件）但是...不知道如何完成该作业。

执行此操作的 C 程序大致如下：

 uncompress( pUncompr , &uncomprLen , (const Bytef*)pDecoded , decodedSize );
 pToBeCorrected = (char *)pUncompr;
 for (n = 0; n < (2 * peaksCount); n++) {
    pPeaks[n] = (RAMPREAL) ((float *) pToBeCorrected)[n];
 }

其中peaksCount 是输入文件中“行”的数量。

编辑（15-2-2012）：我的代码的问题是我没有重建数组，固定代码如下（如果有人需要类似的代码片段，可能会很方便）：

  while ($row = mysql_fetch_array($result, MYSQL_NUM)) {
    $m< = base64_decode($row[4]);
    $mz_int = gzuncompress($int);
    $max = strlen($unc_mz);
    $counter = 0;
    for ($i = 0; $i < $max; $i = $i + 4) {
      $temp= substr($unc_mz,$i,4);
      $temp = unpack("f",$temp);
      $mz_array[$counter] = $temp[1];
      $counter++;
    }

未压缩的字符串必须被切成与浮点长度相对应的块，然后 unpack() 从二进制“块”重建浮点数据。这是我可以对上面的代码片段给出的最简单的描述。

原文

I have a set of ZLIB compressed / base64 encoded strings (done in a C program) that are stored in a database. I have written a small PHP page that should retrieve these values and plot them (the string originally was a list of floats).

Chunk of C program that compresses/encodes:

error=compress2(comp_buffer, &comp_length,(const Bytef*)data.mz ,(uLongf)length,Z_DEFAULT_COMPRESSION); /* compression */
if (error != Z_OK) {fprintf(stderr,"zlib error..exiting"); exit(EXIT_FAILURE);}
mz_binary=g_base64_encode (comp_buffer,comp_length); /* encoding */

(Example) of original input format:

292.1149    8379.5928
366.1519  101313.3906
367.3778   20361.8105
369.1290   17033.3223
375.4355    1159.1841
467.3191    8445.3926

Each column was compressed/encoded as a single string. To reconstruct the original data i am using the following code:

//$row[4] is retrieved from the DB and contains the compressed/encoded string
$mz = base64_decode($row[4]);
$unc_mz = gzuncompress($mz);
echo $unc_mz;

Yet this gives me the following output:

f6jEÍ„]EšiSE@IEfŽ

Could anyone give me a tip/hint about what I might be missing?

------ Added Information -----

I feel that the problem comes from the fact that currently php views $unc_mz as a single string while in reality i would have to re-construct an array containing X lines (this output was from a 9 line file) but... no idea how to do that assignment.

The C program that did that went roughly like this:

 uncompress( pUncompr , &uncomprLen , (const Bytef*)pDecoded , decodedSize );
 pToBeCorrected = (char *)pUncompr;
 for (n = 0; n < (2 * peaksCount); n++) {
    pPeaks[n] = (RAMPREAL) ((float *) pToBeCorrected)[n];
 }

where peaksCount would be the amount of 'lines' in the input file.

EDIT (15-2-2012): The problem with my code was that I was not reconstructing the array, the fixed code is as follows (might be handy if someone needs a similar snippet):

  while ($row = mysql_fetch_array($result, MYSQL_NUM)) {
    $m< = base64_decode($row[4]);
    $mz_int = gzuncompress($int);
    $max = strlen($unc_mz);
    $counter = 0;
    for ($i = 0; $i < $max; $i = $i + 4) {
      $temp= substr($unc_mz,$i,4);
      $temp = unpack("f",$temp);
      $mz_array[$counter] = $temp[1];
      $counter++;
    }

The uncompressed string has to be chopped into chunks corresponding to the length of a float, unpack() then reconstructs the float data from teh binary 'chunk'. That's the simplest description that I can give for the above snippet.

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