fgetcsv
Sometimes the strings you want to read from a file are not separated by an end of line character. the C style getline() function solves this. Here is my version:
<?php
function getline( $fp, $delim )
{
$result = "";
while( !feof( $fp ) )
{
$tmp = fgetc( $fp );
if( $tmp == $delim )
return $result;
$result .= $tmp;
}
return $result;
}
// Example:
$fp = fopen("/path/to/file.ext", 'r');
while( !feof($fp) )
{
$str = getline($fp, '|');
// Do something with $str
}
fclose($fp);
?>
fgets
(PHP 4, PHP 5)
fgets — 从文件指针中读取一行
说明
string fgets
( resource
$handle
[, int $length
] )从文件指针中读取一行。
参数
-
handle -
文件指针必须是有效的，必须指向由 fopen() 或 fsockopen() 成功打开的文件(并还未由 fclose() 关闭)。
-
length -
从
handle指向的文件中读取一行并返回长度最多为length- 1 字节的字符串。碰到换行符（包括在返回值中）、EOF 或者已经读取了 length - 1 字节后停止（看先碰到那一种情况）。如果没有指定length，则默认为 1K，或者说 1024 字节。Note:
从 PHP 4.3 开始，忽略掉 length 则行的长度被假定为 1024，将继续从流中读取数据直到行结束。如果文件中的大多数行都大于 8KB，则在脚本中指定最大行的长度在利用资源上更为有效。
返回值
从指针 handle 指向的文件中读取了 length - 1 字节后返回字符串。
如果文件指针中没有更多的数据了则返回 FALSE。
错误发生时返回 FALSE。
更新日志
| 版本 | 说明 |
|---|---|
| 4.3.0 | fgets() 开始二进制安全 |
| 4.2.0 |
length 参数成为可选。
|
范例
Example #1 逐行读取文件
<?php
$handle = @fopen("/tmp/inputfile.txt", "r");
if ($handle) {
while (($buffer = fgets($handle, 4096)) !== false) {
echo $buffer;
}
if (!feof($handle)) {
echo "Error: unexpected fgets() fail\n";
}
fclose($handle);
}
?>
注释
Note: 在读取在 Macintosh 电脑中或由其创建的文件时， 如果 PHP 不能正确的识别行结束符，启用运行时配置可选项 auto_detect_line_endings 也许可以解决此问题。
Note:
习惯了 C 语言中 fgets() 语法的人应该注意到 EOF 是怎样被返回的。
参见
- fgetss() - 从文件指针中读取一行并过滤掉 HTML 标记
- fread() - 读取文件（可安全用于二进制文件）
- fgetc() - 从文件指针中读取字符
- stream_get_line() - Gets line from stream resource up to a given delimiter
- fopen() - 打开文件或者 URL
- popen() - 打开进程文件指针
- fsockopen() - Open Internet or Unix domain socket connection
- stream_set_timeout() - Set timeout period on a stream
add a note
User Contributed Notes
fgets - [34 notes]
angelo [at] mandato <dot> com ¶
8 years ago
Peter Schlaile ¶
5 years ago
fscanf($file, "%s\n") isn't really a good substitution for fgets(), since it will stop parsing at the first whitespace and not at the end of line!
(See the fscanf page for details on this)
Anonymous ¶
7 years ago
Macintosh line endings mentioned in docs refer to Mac OS Classic. You don't need this setting for interoperability with unixish OS X.
tavernadelleidee[italy] ¶
7 years ago
I think that the quickest way of read a (long) file with the rows in reverse order is
<?php
$myfile = 'myfile.txt';
$command = "tac $myfile > /tmp/myfilereversed.txt";
passthru($command);
$ic = 0;
$ic_max = 100; // stops after this number of rows
$handle = fopen("/tmp/myfilereversed.txt", "r");
while (!feof($handle) && ++$ic<=$ic_max) {
$buffer = fgets($handle, 4096);
echo $buffer."<br>";
}
fclose($handle);
?>
It echos the rows while it is reading the file so it is good for long files like logs.
Borgonovo
dandrews OVER AT 3dohio DOT com ¶
8 years ago
Saku's example may also be used like this:
<?php
@ $pointer = fopen("$DOCUMENT_ROOT/foo.txt", "r"); // the @ suppresses errors so you have to test the pointer for existence
if ($pointer) {
while (!feof($pointer)) {
$preTEXT = fgets($pointer, 999);
// $TEXT .= $preTEXT; this is better for a string
$ATEXT[$I] = $preTEXT; // maybe better as an array
$I++;
}
fclose($pointer);
}
?>
Anonymous ¶
8 years ago
If you need to simulate an un-buffered fgets so that stdin doesnt hang there waiting for some input (i.e. it reads only if there is data available) use this :
<?php
function fgets_u($pStdn) {
$pArr = array($pStdn);
if (false === ($num_changed_streams = stream_select($pArr, $write = NULL, $except = NULL, 0))) {
print("\$ 001 Socket Error : UNABLE TO WATCH STDIN.\n");
return FALSE;
} elseif ($num_changed_streams > 0) {
return trim(fgets($pStdn, 1024));
}
}
?>
timr ¶
8 years ago
If you need to read an entire file into a string, use file_get_contents(). fgets() is most useful when you need to process the lines of a file separately.
afwxkat at gmail dot com ¶
3 years ago
One thing I discovered with fgets, at least with PHP 5.1.6, is that you may have to use an IF statement to avoid your code running rampant (and possibly hanging the server). This can cause problems if you do not have root access on the server on which you are working.
This is the code I have implemented ($F1 is an array):
<?php
if($fh = fopen("filename","r")){
while (!feof($fh)){
$F1[] = fgets($fh,9999);
}
fclose($fh);
}
?>
I have noticed that without the IF statement, fgets seems to ignore when $fh is undefined (i.e., "filename" does not exist). If that happens, it will keep attempting to read from a nonexistent filehandle until the process can be administratively killed or the server hangs, whichever comes first.
Leigh Purdie ¶
4 years ago
For large files, consider using stream_get_line rather than fgets - it can make a significant difference.
$ time yes "This is a test line" | head -1000000 | php -r '$fp=fopen("php://stdin","r"); while($line=stream_get_line($fp,65535,"\n")) { 1; } fclose($fp);'
real 0m1.482s
user 0m1.616s
sys 0m0.152s
$ time yes "This is a test line" | head -1000000 | php -r '$fp=fopen("php://stdin","r"); while($line=fgets($fp,65535)) { 1; } fclose($fp);'
real 0m7.281s
user 0m7.392s
sys 0m0.136s
anacreo has gmail ¶
5 years ago
I'm using this function to modify the header of a large postscript document on copy... Works extremely quickly so far...
function write($filename) {
$fh = fopen($this->sourceps,'r');
$fw = fopen($filename,'w');
while (!feof($fh)) {
$buffer = fgets($fh);
fwrite($fw,$buffer);
if (!$setupfound && ereg("^%%BeginSetup",$buffer)) {
$setupfound++;
if (array_key_exists("$filename",$this->output)) {
foreach ($this->output[$filename] as $function => $value) {
fwrite($fw,$value);
}
}
stream_copy_to_stream($fh,$fw);
}
}
fclose($fw);
fclose($fh);
}
apardo at NOSPAM dot gmail dot com ¶
1 year ago
This is a a simple function to detect end of line type for any file.
<?php
function detectEndOfLine($file)
{
$handle = @fopen($file, "r");
if ($handle)
{
$char=0;
while (!$eol || feof($handle))
{
$char++;
$line = fgets($handle, $char);
$eol = preg_match("/(\r)+/", $line)? "W" : "";
if(!$eol) $eol = preg_match("/(\n)+/", $line)? "L" : "";
}
return $eol;
fclose($handle);
}
}
?>
hgs at cs dot columbia dot edu ¶
2 years ago
There seems to be an interaction between sockets and the auto_detect_line_endings setting that can cause rather peculiar behavior. Apparently, if the first line read from a socket is split across two TCP packets, the detector will look at the first TCP packet and determine that the system uses MacOS (\r) line endings, even though the LF is contained in the next packet. For example, this affected the PEAR Net_SMTP package, which would fail mysteriously for only some email servers.
lzsiga at freemail.c3.hu ¶
2 years ago
Some people try to call feof before fgets, and then ignoring the return value of fgets. This method leads to processing value FALSE when reaching the end of file.
Bad example:
<?php
$f = fopen ("fgetstest.php", "r");
$ln= 0;
while (! feof ($f)) {
$line= fgets ($f);
++$ln;
printf ("%2d: ", $ln);
if ($line===FALSE) print ("FALSE\n");
else print ($line);
}
fclose ($f);
?>
Good example:
<?php
$f = fopen ("fgetstest.php", "r");
$ln= 0;
while ($line= fgets ($f)) {
++$ln;
printf ("%2d: ", $ln);
if ($line===FALSE) print ("FALSE\n");
else print ($line);
}
fclose ($f);
?>
Daniel Klein ¶
5 years ago
The file pointer that fgets() uses can also be created with the proc_open() function and used with the stdout pipe created from the executed process.
david_sitller at blackbit dot de ¶
5 years ago
If you use the example from the command-description, i recommend to trim the $buffer for further use. The line feed ist still at the end of the line. I saw this when using PHP CLI.
Like this, checking a file-list for existing entries:
$handle = fopen ("/tmp/files.txt", "r");
while (!feof($handle)) {
$buffer = fgets($handle, 4096);
if (file_exists(rtrim($filename,"\n"))) {
echo $buffer;
} else {
echo $buffer." has been removed."
}
fclose ($handle);
sam dot bryan at montal dot com ¶
6 years ago
An easy way to authenticate Windows Domain users from scripts running on a non-Windows or non-Domain box - pass the submitted username and password to an IMAP service on a Windows machine.
<?php
$server = 'imapserver';
$user = 'user';
$pass = 'pass';
if (authIMAP($user, $pass, $server)) {
echo "yay";
} else {
echo "nay";
}
function authIMAP($user, $pass, $server) {
$connection = fsockopen($server, 143, $errno, $errstr, 30);
if(!$connection) return false;
$output = fgets($connection, 128); // banner
fputs($connection, "1 login $user $pass\r\n");
$output = fgets($connection, 128);
fputs($connection, "2 logout\r\n");
fclose($connection);
if (substr($output, 0, 4) == '1 OK') return true;
return false;
}
?>
hackajar <matt> yahoo <trot> com ¶
7 years ago
When working with VERY large files, php tends to fall over sideways and die.
Here is a neat way to pull chunks out of a file very fast and won't stop in mid line, but rater at end of last known line. It pulled a 30+ million line 900meg file through in ~ 24 seconds.
NOTE:
$buf just hold current chunk of data to work with. If you try "$buf .=" (note 'dot' in from of '=') to append $buff, script will come to grinding crawl around 100megs of data, so work with current data then move on!
//File to be opened
$file = "huge.file";
//Open file (DON'T USE a+ pointer will be wrong!)
$fp = fopen($file, 'r');
//Read 16meg chunks
$read = 16777216;
//\n Marker
$part = 0;
while(!feof($fp)) {
$rbuf = fread($fp, $read);
for($i=$read;$i > 0 || $n == chr(10);$i--) {
$n=substr($rbuf, $i, 1);
if($n == chr(10))break;
//If we are at the end of the file, just grab the rest and stop loop
elseif(feof($fp)) {
$i = $read;
$buf = substr($rbuf, 0, $i+1);
break;
}
}
//This is the buffer we want to do stuff with, maybe thow to a function?
$buf = substr($rbuf, 0, $i+1);
//Point marker back to last \n point
$part = ftell($fp)-($read-($i+1));
fseek($fp, $part);
}
fclose($fp);
jerem-NoSpam-ified at live dot com ¶
5 years ago
It's worth noting that this function only assumes chr(10) as a line break, but not chr(13). Personally, I prefer using chr(13) as a line break.
David at Weintraub.name ¶
5 years ago
There's an error in the documentation:
The file pointer must be valid, and must point to a file successfully opened by fopen() or fsockopen() (and not yet closed by fclose()).
You should also add "popen" and "pclose" to the documentation. I'm a new PHP developer and went to verify that I could use "fgets" on commands that I used with "popen".
d at foo.com ¶
6 years ago
For sockets, If you dont want fgets, fgetc etc... to block if theres no data there. set socket_set_blocking(handle,false); and socket_set_blocking(handle,true); to set it back again.
ecvej ¶
7 years ago
I would have expected the same behaviour from these bits of code:-
<?php
/*This times out correctly*/
while (!feof($fp)) {
echo fgets($fp);
}
/*This times out before eof*/
while ($line=fgets($fp)) {
echo $line;
}
/*A reasonable fix is to set a long timeout*/
stream_set_timeout($fp, 180);
while ($line=fgets($fp)) {
echo $line;
}
?>
kpeters AT-AT monolithss DEE OH TEE com ¶
7 years ago
It appears that fgets() will return FALSE on EOF (before feof has a chance to read it), so this code will throw an exception:
while (!feof($fh)) {
$line = fgets($fh);
if ($line === false) {
throw new Exception("File read error");
}
}
lelkesa ¶
8 years ago
Note that - afaik - fgets reads a line until it reaches a line feed (\\n). Carriage returns (\\r) aren't processed as line endings.
However, nl2br insterts a <br /> tag before carriage returns as well.
This is useful (but not nice - I must admit) when you want to store a more lines in one.
<?php
function write_lines($text) {
$file = fopen('data.txt', 'a');
fwrite($file, str_replace("\n", ' ', $text)."\n");
fclose($file);
}
function read_all() {
$file = fopen('data.txt', 'r');
while (!feof($file)) {
$line = fgets($file);
echo '<u>Section</u><p>nl2br'.($line).'</p>';
}
fclose($file);
}
?>
Try it.
Pete ¶
9 years ago
If you have troubles reading binary data with versions <= 4.3.2 then upgrade to 4.3.3
The binary safe implementation seems to have had bugs which were fixed in 4.3.3
dan at censornet dot com ¶
1 year ago
WARNING! fgets() and I presume any read() call to a file handle, e.g.
while(!feof(STDIN)) {
$line = fgets(STDIN);
...do something useful with $line...
}
...will result in a timeout after a default time of 60 seconds on my install. This behavior is non standard (not POSIX like) and seems to me to be a bug, or if not a major caveat which should be documented more clearly.
After the timeout fgets() will return FALSE (=== FALSE), however, you can check to see if the stream (file handle) has really closed by checking feof($stream), e.g.
while(!feof(STDIN)) {
$line = fgets(STDIN);
if($line === FALSE) {
if(feof(STDIN)) {
break;
}
continue;
}
...do something useful with $line...
}
rembert at floating-point dot nl ¶
2 years ago
To have fgets get data from a (for instance binary) string this might be of help:
<?php
$data = "the string data\nyou wish\nto parse";
$fp = fopen('data:text/plain,'. $data,'rb');
while ( ($line = fgets($fp)) !== false) {
echo "$line<br>";
}
?>
bens at effortlessis dot com ¶
3 years ago
As I noted in a comment on stream_get_line() page, fgets is *not* necessarily slower than stream_get_line(). In my case, it's actually ~2.5 times slower. (25 seconds vs 10 seconds)
Also, stream_get_line() doesn't return the limiter. Since you pass both a maximum string length, you have no way of knowing whether or not the limiter was present in the original file, other than the 1 in 1024 chance that the line (with limiter) is exactly 1024 characters long, and appending the limiter (EG: "\n") in the case where the line is less than 1024 chars.
This latter bit compromises data integrity, stream_get_line() should probably not be used for all but very special cases.
fm ¶
4 years ago
Here my solution for the \" problem [in CSV files. This function uses fgets(), not fgetcsv().]
<?php
define("CSV_Start", 0);
define("CSV_Quoted", 1);
define("CSV_Quoted2", 2);
define("CSV_Unquoted", 3);
function readCSV($fh, $len, $delimiter = ',', $enclosure = '"') {
$data = Array();
$fildNr = 0;
$state = CSV_Start;
$data[0] = "";
do {
$line = fgets($fh, $len);
for ($ix = 0; $ix < strlen($line); $ix++) {
if ($line[$ix] == $delimiter) {
if ($state != CSV_Quoted) {
$fildNr++;
$data[$fildNr] = "";
$state = CSV_Start;
} else {
$data[$fildNr] .= $line[$ix];
}
} elseif ($line[$ix] == $enclosure) {
if ($state == CSV_Start) {
$state = CSV_Quoted;
} elseif ($state == CSV_Quoted) {
$state = CSV_Quoted2;
} elseif ($state == CSV_Quoted2) {
$data[$fildNr] .= $line[$ix];
$state = CSV_Quoted;
} else {
$data[$fildNr] .= $line[$ix];
}
} else {
$data[$fildNr] .= $line[$ix];
if ($state == CSV_Quoted2) {
echo "error";
} elseif ($state == CSV_Start) {
$state = CSV_Unquoted;
}
}
}
} while ($state == CSV_Quoted);
return $data;
}
?>
rahil123 at gmail dot com ¶
4 years ago
As fgets uses char(10) LF as separator instead of ch(13) CF is caused me problem in using the read value(e.g. "XYZ\n" in system() command(e.g. system("XYZ\n option") was interpreted as only system("XYZ") due to \n). \n would have to striped out first.
soapergem at gmail dot com ¶
4 years ago
I ran into an issue that took me forever to finally figure out today, and I wanted to post my findings here in case anyone else ever runs into the same thing. I had tried to open a connection using fsockopen to my own server, send some data with fwrite, and then read the response with fgets. The data I sent over included the session ID, which was to be loaded by the page receiving it. Keep in mind that both the sender and receiver URLs were on my same server, and both tried to use the same session ID.
I found that I could do the fwrite part just fine, but that fgets would lock up indefinitely, ignoring any timeout I had set with fsockopen (but thankfully still obeying the max_execution_time limit).
The problem was that while the sending page was trying to do the fgets, it still had the session open. But the receiving page needed session data before it was willing to output anything, thereby creating a deadlock.
The solution I found was to call session_write_close() just prior to sending the request in the sender page, thereby granting access for the receiver to open up the session variables it needed.
julian dot chappell at NOSPAM dot btopenworld dot com ¶
4 years ago
Reply to Jerem's note. fgets terminating on chr(10) is correct.
For the sake of you youngsters who have never heard of such things, the protocol for the CRLF pair dates back to the days where the input/output with computers was on teletype machines. A sort of glorified typewriter.
chr(13) is a carriage return (CR), a command which physically moved the type head to the home position and chr(10) is a line feed (LF), which moved the paper up a line.
The standard order in which these were used was CRLF - chr(13)/chr(10) - and both were needed for a line break. Use a CR chr(13) on its own and you would overwrite the beginning of the same line. (Incidentally, this was how bold type was done - print the same thing in the same place twice!). Use LF chr(10) on its own and you would continue printing at the current position across the page but dropped down a line. (Because the paper would move up but the print head remain where it is).
Usage of this protocol has become somewhat sloppy and ill-defined these days for both printers and monitors. Some applications expect a line feed chr(10) on its own and simply assume a carriage return, others still use both but often without observing their distinctly separate functions. So much so that it may sometimes appear that they both do more or less the same thing, you only need one of them, and which to use is purely a matter of personal choice. Wrong on all counts!
fgets terminating on a LF chr(10) is correct as it ensures that the preceding CR chr(13) is included in the line if it is present - and doesn't matter if it isn't. If fgets ever terminated on CR chr(13) as jerem suggests more often than not there would be a LF at the beginning of the next line read.
The prefered use of chr(13) alone as a line break is risky. You might get away with it using your own applications and current printer, but if your file is for general release other people would see the entire output of your file printed on the same line if they use applications that interpret the CRLF pair more correctly. Not what you intended!
svayn at yahoo dot com ¶
6 years ago
fgets is SLOW for scanning through large files. If you don't have PHP 5, use fscanf($file, "%s\n") instead.
Saku ¶
8 years ago
As a beginner I would have liked to see "how to read a file into a string for use later and not only how to directly echo the fgets() result. This is what I derived:
<?php
@ $pointer = fopen("$DOCUMENT_ROOT/foo.txt", "r"); // the @ suppresses errors so you have to test the pointer for existence
if ($pointer) {
while (!feof($pointer)) {
$preTEXT = fgets($pointer, 999);
$TEXT = $TEXT . $preTEXT;
}
fclose($pointer);
}
?>
guntars at datapro dot lv ¶
9 years ago
For all those people struggling with Macintosh conversions, since PHP 4.3 there is a new runtime setting available:
auto_detect_line_endings boolean
When turned on, PHP will examine the data read by fgets() and file() to see if it is using Unix, MS-Dos or Macintosh line-ending conventions.
This enables PHP to interoperate with Macintosh systems, but defaults to Off, as there is a very small performance penalty when detecting the EOL conventions for the first line, and also because people using carriage-returns as item separators under Unix systems would experience non-backwards-compatible behaviour.