How many arrays does php divide into?

PHP is a commonly used server-side scripting language and one of the important tools for large-scale website development. In PHP, for a string, we can use the split() function to split it into an array. However, the split() function has been abandoned in PHP 7.0 version. How to split a string? This article will introduce how to use functions such as explode() to split strings in PHP, and discuss how to optimize the code and improve program efficiency.

1. Use the explode() function to split a string

Theexplode() function is one of the commonly used functions in PHP to split a string. The following is the format:

array explode(string $delimiter, string $string [, int $limit = PHP_INT_MAX])

Among them, $delimiter is the split identifier and $string is the split string, the $limit parameter is optional and is used to limit the number of splits. The default is PHP_INT_MAX, which means unlimited times. This function returns an array, splitting the string into parts, each part becoming an element of the array.

For example:

$str = "apple, orange, banana, pear";
$arr = explode(", ", $str);
print_r($arr);

Output result:

Array ( [0] => apple [1] => orange [2] => banana [3] => pear )

2. Use str_split() function to split the string

str_split() function splits the string into Multiple characters, returns a character array. The following is the format:

array str_split(string $string [, int $split_length = 1])

Among them, $string is the split string, and the $split_length parameter is optional. Used to limit the length of each section, default value is 1. This function returns an array that splits the string into characters, with each character becoming an element of the array.

For example:

$str = "abcde";
$arr = str_split($str);
print_r($arr);

Output result:

Array ( [0] => a [1] => b [2] => c [3] => d [4] => e )

3. Use the preg_split() function to split the string

preg_split() function and explode() function Similarly, it is also a function used to split strings. However, this function uses regular expressions as identifiers for splitting, so it can be split based on more complex rules. The following is the format:

array preg_split(string $pattern, string $string [, int $limit = -1 [, int $flags = 0]])

where $pattern is as Regular expression for splitting identifiers. $string is the string to be split. The $limit parameter is optional and is used to limit the number of splits. The default is -1, indicating unlimited times. The $flags parameter is optional. Used to set the matching pattern of regular expressions. This function returns an array, splitting the string into parts, each part becoming an element of the array.

For example:

$str = "apple, orange, banana, pear";
$arr = preg_split("/, /", $str);
print_r($arr);

Output result:

Array ( [0] => apple [1] => orange [2] => banana [3] => pear )

4. Use the strtok() function to split the string

The strtok() function splits the string into one Series tag, returns a string. The following is the format:

string strtok(string $string, string $token)

Among them, $string is the split string, and $token is the string used as the split identifier. This function returns the first token separated, or false if there are no more tokens.

For example:

$str = "apple, orange, banana, pear";
$token = ", ";
$next = strtok($str, $token);
while ($next !== false) {
  echo $next . "<br>";
  $next = strtok($token);
}

Output result:

apple
orange
banana
pear

5. How to optimize code and improve program efficiency

In PHP, how to optimize code and improve program efficiency What about efficiency? The following are some commonly used methods:

1. Use appropriate functions, such as using the most suitable function when splitting strings, such as explode(), str_split(), preg_split() and strtok() and other functions.
2. Avoid repeated operations. For example, in a loop, some calculation results can be cached to avoid repeated calculations.
3. Close unnecessary functions and extensions. There are many unnecessary functions and extensions in PHP. You can turn them off by setting them in the php.ini file, thereby improving the efficiency of the program.
4. Use cache appropriately. You can use caching technologies such as memcached and redis to cache some frequently read data, thereby avoiding operations such as multiple database queries.

In short, when developing PHP programs, we should pay attention to the efficiency of the program, select functions reasonably, and pay attention to code optimization, thereby improving program efficiency and user experience.

Conclusion

This article introduces the commonly used string splitting functions in PHP, including functions such as explode(), str_split(), preg_split() and strtok(), and discusses how to optimize PHP program to improve program efficiency. I hope this article can be helpful to PHP developers.

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