php resource to string
stream_get_contents
stream_get_contents — Reads remainder of a stream into a string
Description
Parameters
A stream resource (e.g. returned from fopen() )
Seek to the specified offset before reading. If this number is negative, no seeking will occur and reading will start from the current position.
Return Values
Returns a string or false on failure.
Examples
Example #1 stream_get_contents() example
Notes
See Also
User Contributed Notes 5 notes
In that case when stream_get_contents/fread/fgets or other stream reading functions block indefinitely your script because they don’t reached the limit of bytes to read use the socket_get_meta_data function to figure out the number of the bytes to read. It returns an array that contains a key named ‘unread_bytes’ and then pass that number to your favourite stream reading functions second parameter to read from the stream.
Maybe a good workaround to use the stream_select function, and set the socket to non-blocking mode with the use of stream_set_blocking($stream, 0). In this case the socket reading functions work properly.
It is important to know that stream_get_contents behaves differently with different versions of PHP. Consider the following
/**
*
* ‘file’ content
*
* PHP 5.1.6:
* 67895
*
* PHP 5.2.17:
* 123456789
*
*/
?>
As a result, stream_get_contents() affects file position in 5.1, and do not affect file position in 5.2 or better.
Creating streams from strings in PHP
I’m in the process of writing an API that relies on (file-)streams to be passed around.
There are situations where a string instead needs to be used, and for these purposes the data: stream wrapper is used. Initially I thought it was only possible to encode the actual string in base64, which I didn’t like because of the added footprint.
Quickly checking out the rfc, it turns out that ‘;base64’ can be omitted to just pass along the raw data, which makes a lot more sense in the context of PHP.
Thankfully, PHP gladly supports it:
Update June 23th, 2013
Just in case anyone stumbles upon this, I would no longer recommend using the data uri for this purpose.
This is how you use it:
A bit more info can be found on php.net.
Web mentions
Comments
My favorite usage of the data: wrapper is for raw uploaded csv data. If you let user’s cut-n-paste a csv for upload you can use the data: wrapper to fopen the POST data then fgetcsv() on it to save yourself from parsing it manually.
Great tip, thanks! I might use this to simplify some code I have that works with either IPC pipes or strings.
@Josh: Thanks for an awesome example of how to use it.
aparimana • Jun 23, 2013
I should really update this post, but I would _not_ recommend using the data:// url. Use php://memory and php://temp instead!
Nicholas Ruunu • Apr 23, 2017
Is it possible to write initial data to a read only stream with php://temp?
Markus • Nov 25, 2013
instead of base64_encode() in php which consumes a lot of php memory you should use
stream_filter_append($fh, ‘convert.base64-encode’);
which is not limited by php-memory limits AFAIK
Jasmine Hegman • Jul 28, 2015
r+ actually works too. Judging from the documentation is looks like the only difference is that w+ creates a new file if it doesn’t already exist, but that’s not really relevant here.
Jasmine Hegman • Jul 30, 2015
Oh you are so right, I don’t know what I was thinking! I guess my brain decided to pretend the + symbol was meaningless. :3
linoge • Jun 04, 2016
Thank you very much for the article, I was looking exactly for this, and it’s such a nice thing that you added the update c;
Matt Styles • Jun 24, 2016
Beautiful, thank you!
Hugo Franco de Campos • Nov 30, 2016
Is there any concern about keep large strings in memory using fopen? I’m sending a large csv string to a file storage and I have no idea if I should use memory, temp or anything else.
rinogo • Sep 02, 2017
Thanks for your short examples on this, especially for the 2013 update! Exactly what I was looking for.
Php resource to string
When a string is specified in double quotes or with heredoc, variables are parsed within it.
There are two types of syntax: a simple one and a complex one. The simple syntax is the most common and convenient. It provides a way to embed a variable, an array value, or an object property in a string with a minimum of effort.
The complex syntax can be recognised by the curly braces surrounding the expression.
Simple syntax
Exemplul de mai sus va afișa:
Similarly, an array index or an object property can be parsed. With array indices, the closing square bracket ( ] ) marks the end of the index. The same rules apply to object properties as to simple variables.
Example #10 Simple syntax example
$people = new people ();
Exemplul de mai sus va afișa:
As of PHP 7.1.0 also negative numeric indices are supported.
Example #11 Negative numeric indices
Exemplul de mai sus va afișa:
For anything more complex, you should use the complex syntax.
Complex (curly) syntax
This isn’t called complex because the syntax is complex, but because it allows for the use of complex expressions.
// Show all errors
error_reporting ( E_ALL );
echo «This is the value of the var named by the return value of getName(): <$< getName ()>> » ;
// Won’t work, outputs: This is the return value of getName():
echo «This is the return value of getName():
?>
It is also possible to access class properties using variables within strings using this syntax.
Exemplul de mai sus va afișa:
The value accessed from functions, method calls, static class variables, and class constants inside <$>will be interpreted as the name of a variable in the scope in which the string is defined. Using single curly braces ( <> ) will not work for accessing the return values of functions or methods or the values of class constants or static class variables.
// Show all errors.
error_reporting ( E_ALL );
$rootbeer = ‘A & W’ ;
$ipa = ‘Alexander Keith\’s’ ;
String access and modification by character
Notă: As of PHP 7.1.0, negative string offsets are also supported. These specify the offset from the end of the string. Formerly, negative offsets emitted E_NOTICE for reading (yielding an empty string) and E_WARNING for writing (leaving the string untouched).
Internally, PHP strings are byte arrays. As a result, accessing or modifying a string using array brackets is not multi-byte safe, and should only be done with strings that are in a single-byte encoding such as ISO-8859-1.
Notă: As of PHP 7.1.0, applying the empty index operator on an empty string throws a fatal error. Formerly, the empty string was silently converted to an array.
Example #12 Some string examples
String offsets have to either be integers or integer-like strings, otherwise a warning will be thrown.
Example #13 Example of Illegal String Offsets
Exemplul de mai sus va afișa:
Accessing characters within string literals using the <> syntax has been deprecated in PHP 7.4. This has been removed in PHP 8.0.
Useful functions and operators
String s may be concatenated using the ‘.’ (dot) operator. Note that the ‘+’ (addition) operator will not work for this. See String operators for more information.
There are a number of useful functions for string manipulation.
See the string functions section for general functions, and the Perl-compatible regular expression functions for advanced find & replace functionality.
There are also functions for URL strings, and functions to encrypt/decrypt strings (Sodium and Hash).
Converting to string
An int or float is converted to a string representing the number textually (including the exponent part for float s). Floating point numbers can be converted using exponential notation ( 4.1E+6 ).
In order to convert object s to string magic method __toString must be used.
null is always converted to an empty string.
Most PHP values can also be converted to string s for permanent storage. This method is called serialization, and is performed by the serialize() function.
Details of the String Type
The string in PHP is implemented as an array of bytes and an integer indicating the length of the buffer. It has no information about how those bytes translate to characters, leaving that task to the programmer. There are no limitations on the values the string can be composed of; in particular, bytes with value 0 (“NUL bytes”) are allowed anywhere in the string (however, a few functions, said in this manual not to be “binary safe”, may hand off the strings to libraries that ignore data after a NUL byte.)
This nature of the string type explains why there is no separate “byte” type in PHP – strings take this role. Functions that return no textual data – for instance, arbitrary data read from a network socket – will still return strings.
Given that PHP does not dictate a specific encoding for strings, one might wonder how string literals are encoded. For instance, is the string «á» equivalent to «\xE1» (ISO-8859-1), «\xC3\xA1» (UTF-8, C form), «\x61\xCC\x81» (UTF-8, D form) or any other possible representation? The answer is that string will be encoded in whatever fashion it is encoded in the script file. Thus, if the script is written in ISO-8859-1, the string will be encoded in ISO-8859-1 and so on. However, this does not apply if Zend Multibyte is enabled; in that case, the script may be written in an arbitrary encoding (which is explicitly declared or is detected) and then converted to a certain internal encoding, which is then the encoding that will be used for the string literals. Note that there are some constraints on the encoding of the script (or on the internal encoding, should Zend Multibyte be enabled) – this almost always means that this encoding should be a compatible superset of ASCII, such as UTF-8 or ISO-8859-1. Note, however, that state-dependent encodings where the same byte values can be used in initial and non-initial shift states may be problematic.
Of course, in order to be useful, functions that operate on text may have to make some assumptions about how the string is encoded. Unfortunately, there is much variation on this matter throughout PHP’s functions:
Ultimately, this means writing correct programs using Unicode depends on carefully avoiding functions that will not work and that most likely will corrupt the data and using instead the functions that do behave correctly, generally from the intl and mbstring extensions. However, using functions that can handle Unicode encodings is just the beginning. No matter the functions the language provides, it is essential to know the Unicode specification. For instance, a program that assumes there is only uppercase and lowercase is making a wrong assumption.
Конвертировать массив в строку при помощи PHP
Если вам потребовалось преобразовать массив php в строку, то для этого есть несколько инструментов. Применение того или иного инструмента зависит от ваших целей.
Теперь поговорим о конвертации массива в строку:
1. Функция implode()
С ее помощью можно «склеить» элементы массива в строку, через любой разделитель. Подробнее: implode
Пример:
Подобным образом мы можем преобразовать только одномерные массивы и у нас пропадут ключи.
2. Функция join()
Работает точно так же как и implode(), поскольку это просто псевдоним, выбирайте название, которое больше нравится.
Пример у нас будет идентичный:
3. Функция serialize()
Затем из этой строки, можно снова получить массив:
4. Функция json_encode()
Возвращает JSON представление данных. В нашем случае, данная функция, напоминает сериализацию, но JSON в основном используется для передачи данных. Вам придется использовать этот формат для обмена данными с javascript, на фронтенде. Подробнее: json_encode
Обратная функция json_decode() вернет объект с типом stdClass, если вторым параметром функции будет false. Либо вернет ассоциативный массив, если передать true вторым параметром
5. Функция print_r
Она подходит для отладки вашего кода. Например вам нужно вывести массив на экран, чтобы понять, какие элементы он содержит.
6. Функция var_dump
Функция var_dump также пригодится для отладки. Она может работать не только с массивами, но и с любыми другими переменными, содержимое которых вы хотите проверить.
7. Функция var_export
var_dump не возвращает значение, но при желании это конечно можно сделать через буферизацию.
array_to_string
Как таковой функции array_to_string в php нет, но есть описанные выше инструменты, которых более чем достаточно для выполнения задачи. Я просто хотел напомнить, что вы никогда не ограничены этими инструментами, и можете написать то, что подходит именно под вашу задачу.
Как сделать работу с массивами еще проще?
Если вы используете библиотеку для работы с коллекциями, то ваш код для преобразования массива в строку может выглядеть куда более изящно:
Также рекомендую обратить внимание на полезную библиотеку для работы со строками. С ее помощью вы можете выполнять операции со строками более удобно и с меньшим количеством кода.
На этом все. Обязательно прочитайте справку по данным функциям и пишите если у вас остались вопросы.
How to convert an array to a string in PHP?
For an array like the one below; what would be the best way to get the array values and store them as a comma-separated string?
8 Answers 8
I would turn it into CSV form, like so:
You can turn it back by doing:
I would turn it into a json object, with the added benefit of keeping the keys if you are using an associative array:
serialize() and unserialize() convert between php objects and a string representation.
PHP has a built-in function implode to assign array values to string. Use it like this:
You can use it like so:
Not the answer you’re looking for? Browse other questions tagged php arrays or ask your own question.
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