php 为什么我的 Content-Length 标头错误？
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Why is my Content-Length header wrong?
提问by kobra
I am trying to find out the exact length of a string using strlen() in php 5.2. The string ($data) contains '\t' and '\n'.
我试图在 php 5.2 中使用 strlen() 找出字符串的确切长度。字符串 ($data) 包含 '\t' 和 '\n'。
echo strlen($data);
Code:
代码：
// fetch table header
$header = '';
while ($fieldData = $result->fetch_field()) {
$header .= $fieldData->name . "\t";
}
// fetch data each row, store on tabular row data
while ($row = $result->fetch_assoc()) {
$line = '';
foreach($row as $value){
if(!isset($value) || $value == ""){
$value = "\t";
}else{
// important to escape any quotes to preserve them in the data.
$value = str_replace('"', '""', $value);
// needed to encapsulate data in quotes because some data might be multi line.
// the good news is that numbers remain numbers in Excel even though quoted.
$value = '"' . $value . '"' . "\t";
}
$line .= $value;
}
$data .= trim($line)."\n";
}
// this line is needed because returns embedded in the data have "\r"
// and this looks like a "box character" in Excel
$data = str_replace("\r", "", $data);
// Nice to let someone know that the search came up empty.
// Otherwise only the column name headers will be output to Excel.
if ($data == "") {
$data = "\nno matching records found\n";
}
// create table header showing to download a xls (excel) file
header("Content-type: application/octet-stream");
header("Content-Disposition: attachment; filename=$export_filename");
header("Cache-Control: public");
header("Content-length: " . strlen($data); // tells file size
header("Pragma: no-cache");
header("Expires: 0");
// output data
echo $header."\n".$data;
This does not return the exact length (its less than the actual length). Please advice.
这不会返回确切的长度（小于实际长度）。请指教。
回答by Paul Dixon
You are telling the user agent to expect strlen($data) and then actually sending $header."\n".$data! Try something like this at the end of your code...
你告诉用户代理期待 strlen($data) 然后实际发送 $header."\n".$data! 在代码的末尾尝试这样的事情......
$output=$header."\n".$data;
// create table header showing to download a xls (excel) file
header("Content-type: application/octet-stream");
header("Content-Disposition: attachment; filename=$export_filename");
header("Cache-Control: public");
header("Content-length: " . strlen($output); // tells file size
header("Pragma: no-cache");
header("Expires: 0");
// output data
echo $output;
回答by mooyah
The content-length header does NOT include the length of the headers plus the body of the response.
content-length 标头不包括标头的长度加上响应的正文。
Content-Length:The length of the response body in octets (8-bit bytes)
Content-Length：以八位字节为单位的响应正文的长度（8 位字节）
Just FYI since the variables used in the "answer" are header + data. Do not be misled.
仅供参考，因为“答案”中使用的变量是标题+数据。不要被误导。
回答by webbiedave
回答by good_evening
Before getting length of string, delete '\t'and '\n'symbols from $datawith str_replaceor with other function like that if strlen()really has bug (I haven't checked that).
在获取字符串长度之前，如果确实有错误（我还没有检查过），请从with或 with 其他函数中删除'\t'和'\n'符号。$datastr_replacestrlen()
回答by Micke
You echo both $headerand $data, but you only set Content-Lengthto the size of $data.
您同时回显$header和$data，但您只设置Content-Length了 的大小$data。
If $headercontains additional HTTP-headers, you should output $headerusing header(). Otherwise, you should set Content-Lengthto strlen($header."\n".$data).
如果$header包含额外的 HTTP 标头，则应$header使用header(). 否则，您应该设置Content-Length为strlen($header."\n".$data).
