I am trying to find out the exact length of a string using strlen() in php 5.2. The string ($data) contains '\\t' and '\\n'.
echo strlen($data);
Code:
// 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.
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...
$output=$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;
strlen returns the correct answer:
echo strlen("1\n2\t3");
// prints 5
You will need to examine your input more carefully.
You echo both $header
and $data
, but you only set Content-Length
to the size of $data
.
If $header
contains additional HTTP-headers, you should output $header
using header()
. Otherwise, you should set Content-Length
to strlen($header."\\n".$data)
.
在获取字符串长度之前,使用str_replace
或其他函数从$data
删除'\\t'
和'\\n'
符号,如果strlen()
确实有bug(我没有检查过)。
The content-length header does NOT include the length of the headers plus the body of the response.
Content-Length: The length of the response body in octets (8-bit bytes)
Just FYI since the variables used in the "answer" are header + data. Do not be misled.
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