Как посчитать количество символов в строке php

iconv_strlen

В отличие от strlen() , iconv_strlen() учитывает кодировку строки. Длина string не обязательно будет соответствовать количеству байт в ней, так как в различных кодировках различные символы кодируются различным количеством байт, например, юникод может быть и двух-, и четырёхбайтным.

Список параметров

Если параметр encoding опущен, предполагается, что кодировка строки string эквивалентна значению iconv.internal_encoding.

Возвращаемые значения

Возвращает количество символов в string как целое число или false в случае возникновения ошибки при кодировании.

Список изменений

Смотрите также

• grapheme_strlen() — Получает длину строки в единицах графемы
• mb_strlen() — Получает длину строки
• strlen() — Возвращает длину строки

User Contributed Notes 2 notes

17 years ago

If iconv_strlen is passed a UTF-8 string containing badly formed sequences, it will return FALSE. This is in contrast to mb_strlen of the behaviour of utf8_decode, which strip out any bad sequences;

# UTF-8 string containing bad sequence: \xe9
$str = «I?t?rn?ti?n\xe9?liz?ti?n» ;

print «mb_strlen: » . mb_strlen ( $str , ‘UTF-8’ ). «\n» ;
print «strlen/utf8_decode: » . strlen ( utf8_decode ( $str )). «\n» ;
print «iconv_strlen: » . iconv_strlen ( $str , ‘UTF-8’ ). «\n» ;
?>

Displays;

mb_strlen: 20
strlen/utf8_decode: 20
iconv_strlen:

As such it is being «stricter» than mb_strlen and it may mean you need to check for invalid sequences first. A quick way to check is to exploit the behaviour of the PCRE extension (see notes on pattern modifiers);

if ( preg_match ( ‘/^./us’ , $str , $ar ) != 1 ) die( «string contains invalid UTF-8» );
>
?>

A slower but stricter check (regex) can be found at: http://www.w3.org/International/questions/qa-forms-utf-8

Similiar applies to iconv_substr, iconv_strpos and iconv_strrpos

3 years ago

Notice there is a disconnect:
>If charset`parameter is omitted, str is assumed to be encoded in iconv.internal_encoding.

But clicking on the iconv.internal_encoding link (https://www.php.net/manual/en/iconv.configuration.php), the docs indicate that iconv.internal_encoding is deprecated since 5.6.

• Функции iconv
  • iconv_​get_​encoding
  • iconv_​mime_​decode_​headers
  • iconv_​mime_​decode
  • iconv_​mime_​encode
  • iconv_​set_​encoding
  • iconv_​strlen
  • iconv_​strpos
  • iconv_​strrpos
  • iconv_​substr
  • iconv
  • ob_​iconv_​handler
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  strlen

  Замечание:

  Функция strlen() возвратит количество байт, а не число символов в строке.

  Смотрите также

  • count() — Подсчитывает количество элементов массива или Countable объекте
  • grapheme_strlen() — Получает длину строки в единицах графемы
  • iconv_strlen() — Возвращает количество символов в строке
  • mb_strlen() — Получает длину строки

  User Contributed Notes 7 notes

  7 years ago

  I want to share something seriously important for newbies or beginners of PHP who plays with strings of UTF8 encoded characters or the languages like: Arabic, Persian, Pashto, Dari, Chinese (simplified), Chinese (traditional), Japanese, Vietnamese, Urdu, Macedonian, Lithuanian, and etc.
  As the manual says: «strlen() returns the number of bytes rather than the number of characters in a string.», so if you want to get the number of characters in a string of UTF8 so use mb_strlen() instead of strlen().

  // the Arabic (Hello) string below is: 59 bytes and 32 characters
  $utf8 = «السلام علیکم ورحمة الله وبرکاته!» ;

  var_export ( strlen ( $utf8 ) ); // 59
  echo «
  » ;
  var_export ( mb_strlen ( $utf8 , ‘utf8’ ) ); // 32
  ?>

  7 years ago

  When checking for length to make sure a value will fit in a database field, be mindful of using the right function.

  There are three possible situations:

  1. Most likely case: the database column is UTF-8 with a length defined in unicode code points (e.g. mysql varchar(200) for a utf-8 database).

  // ok if php.ini default_charset set to UTF-8 (= default value)
  mb_strlen ( $value );
  iconv_strlen ( $value );
  // always ok
  mb_strlen ( $value , «UTF-8» );
  iconv_strlen ( $value , «UTF-8» );

  // BAD, do not use:
  strlen ( utf8_decode ( $value )); // breaks for some multi-byte characters
  grapheme_strlen ( $value ); // counts graphemes, not code points
  ?>

  2. The database column has a length defined in bytes (e.g. oracle’s VARCHAR2(200 BYTE))

  // ok, but assumes mbstring.func_overload is 0 in php.ini (= default value)
  strlen ( $value );
  // ok, forces count in bytes
  mb_strlen ( $value , «8bit» )
  ?>

  3. The database column is in another character set (UTF-16, ISO-8859-1, etc. ) with a length defined in characters / code points.

  Find the character set used, and pass it explicitly to the length function.

  1 year ago

  Since PHP 8.0, passing null to strlen() is deprecated. To check for a blank string (not including ‘0’):

  // PHP >= 8.0
  if ( $text === null || $text === » )) echo ’empty’ ;
  >

  10 years ago

  PHP’s strlen function behaves differently than the C strlen function in terms of its handling of null bytes (‘\0’).

  In PHP, a null byte in a string does NOT count as the end of the string, and any null bytes are included in the length of the string.

  For example, in PHP:

  strlen( «te\0st» ) = 5

  In C, the same call would return 2.

  Thus, PHP’s strlen function can be used to find the number of bytes in a binary string (for example, binary data returned by base64_decode).

  11 years ago

  I would like to demonstrate that you need more than just this function in order to truly test for an empty string. The reason being that will return 0. So how do you know if the value was null, or truly an empty string?

  $foo = null ;
  $len = strlen ( null );
  $bar = » ;

  echo «Length: » . strlen ( $foo ) . «
  » ;
  echo «Length: $len
  » ;
  echo «Length: » . strlen ( null ) . «
  » ;

  if ( strlen ( $foo ) === 0 ) echo ‘Null length is Zero
  ‘ ;
  if ( $len === 0 ) echo ‘Null length is still Zero
  ‘ ;

  Null length is Zero
  Null length is still Zero

  !is_null(): $foo is probably null
  isset(): $foo is probably null

  !is_null(): $bar is truly an empty string
  isset(): $bar is truly an empty string
  // End Output

  So it would seem you need either is_null() or isset() in addition to strlen() if you care whether or not the original value was null.

  13 years ago

  We just ran into what we thought was a bug but turned out to be a documented difference in behavior between PHP 5.2 & 5.3. Take the following code example:

  $attributes = array( ‘one’ , ‘two’ , ‘three’ );

  if ( strlen ( $attributes ) == 0 && ! is_bool ( $attributes )) echo «We are in the ‘if’\n» ; // PHP 5.3
  > else echo «We are in the ‘else’\n» ; // PHP 5.2
  >

  ?>

  This is because in 5.2 strlen will automatically cast anything passed to it as a string, and casting an array to a string yields the string «Array». In 5.3, this changed, as noted in the following point in the backward incompatible changes in 5.3 (http://www.php.net/manual/en/migration53.incompatible.php):

  «The newer internal parameter parsing API has been applied across all the extensions bundled with PHP 5.3.x. This parameter parsing API causes functions to return NULL when passed incompatible parameters. There are some exceptions to this rule, such as the get_class() function, which will continue to return FALSE on error.»

  So, in PHP 5.3, strlen($attributes) returns NULL, while in PHP 5.2, strlen($attributes) returns the integer 5. This likely affects other functions, so if you are getting different behaviors or new bugs suddenly, check if you have upgraded to 5.3 (which we did recently), and then check for some warnings in your logs like this:

  strlen() expects parameter 1 to be string, array given in /var/www/sis/lib/functions/advanced_search_lib.php on line 1028

  If so, then you are likely experiencing this changed behavior.

  6 years ago

  There’s a LOT of misinformation here, which I want to correct! Many people have warned against using strlen(), because it is «super slow». Well, that was probably true in old versions of PHP. But as of PHP7 that’s definitely no longer true. It’s now SUPER fast!

  I created a 20,00,000 byte string (~20 megabytes), and iterated ONE HUNDRED MILLION TIMES in a loop. Every loop iteration did a new strlen() on that very, very long string.

  The result: 100 million strlen() calls on a 20 megabyte string only took a total of 488 milliseconds. And the strlen() calls didn’t get slower/faster even if I made the string smaller or bigger. The strlen() was pretty much a constant-time, super-fast operation

  So either PHP7 stores the length of every string as a field that it can simply always look up without having to count characters. Or it caches the result of strlen() until the string contents actually change. Either way, you should now never, EVER worry about strlen() performance again. As of PHP7, it is super fast!

  Here is the complete benchmark code if you want to reproduce it on your machine:

  $iterations = 100000000 ; // 100 million
  $str = str_repeat ( ‘0’ , 20000000 );

  // benchmark loop and variable assignment to calculate loop overhead
  $start = microtime ( true );
  for( $i = 0 ; $i < $iterations ; ++ $i ) $len = 0 ;
  >
  $end = microtime ( true );
  $loop_elapsed = 1000 * ( $end — $start );

  // benchmark strlen in a loop
  $len = 0 ;
  $start = microtime ( true );
  for( $i = 0 ; $i < $iterations ; ++ $i ) $len = strlen ( $str );
  >
  $end = microtime ( true );
  $strlen_elapsed = 1000 * ( $end — $start );

  // subtract loop overhead from strlen() speed calculation
  $strlen_elapsed -= $loop_elapsed ;

  echo «\nstring length: < $len >\ntest took: < $strlen_elapsed >milliseconds\n» ;

  Уроки PHP — strlen — количество символов в строке

  strlen — оператор, благодаря которому можно совершенно точно узнать количество символов в строке. Что важно — символом считается так же пробел, потому учитывайте этот фактор.

  Использовать этот оператор крайне легко:

  $name = strlen(«Oleksiy Lavrynenko»); //задали переменную, и попросили посчитать количество символов
  echo $name; //вывели на экран количество символов в переменной
  ?>

  Итогом данного кода будет число «18» — количество символов в моем имени и фамилии + пробел.

  Как найти количество символов в строке в PHP

  Вы можете просто использовать PHP-функцию strlen() , чтобы найти количество символов в строке текста. Функция также посчитает пробелы внутри указанной строки.

  Давайте посмотрим на следующий пример, чтобы понять, как это работает:

  

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