implode()

(PHP 4, PHP 5, PHP 7)

将一个一维数组的值转化为字符串

说明

implode(string $glue, array $pieces) : string

implode( array $pieces) : string

用$glue将一维数组的值连接为一个字符串。

Note:

因为历史原因，implode()可以接收两种参数顺序，但是explode()不行。不过按文档中的顺序可以避免混淆。

参数

$glue

默认为空的字符串。

$pieces

你想要转换的数组。

返回值

返回一个字符串，其内容为由 glue 分割开的数组的值。

范例

Example #1implode()例子

<?php
$array = array('lastname', 'email', 'phone');
$comma_separated = implode(",", $array);
echo $comma_separated; // lastname,email,phone
// Empty string when using an empty array:
var_dump(implode('hello', array())); // string(0) ""
?>

注释

Note:此函数可安全用于二进制对象。

参见

• explode()使用一个字符串分割另一个字符串
• preg_split()通过一个正则表达式分隔字符串
• http_build_query()生成 URL-encode 之后的请求字符串

it should be noted that an array with one or no elements works fine. for example:
<?php
  $a1 = array("1","2","3");
  $a2 = array("a");
  $a3 = array();
  
  echo "a1 is: '".implode("','",$a1)."'<br>";
  echo "a2 is: '".implode("','",$a2)."'<br>";
  echo "a3 is: '".implode("','",$a3)."'<br>";
?>
will produce:
===========
a1 is: '1','2','3'
a2 is: 'a'
a3 is: ''

Can also be used for building tags or complex lists, like the following:
<?php
$elements = array('a', 'b', 'c');
echo "<ul><li>" . implode("</li><li>", $elements) . "</li></ul>";
?>
This is just an example, you can create a lot more just finding the right glue! ;)

It's not obvious from the samples, if/how associative arrays are handled. The "implode" function acts on the array "values", disregarding any keys:
<?php
declare(strict_types=1);
$a = array( 'one','two','three' );
$b = array( '1st' => 'four', 'five', '3rd' => 'six' );
echo implode( ',', $a ),'/', implode( ',', $b );
?>
outputs:
one,two,three/four,five,six

It might be worthwhile noting that the array supplied to implode() can contain objects, provided the objects implement the __toString() method.
Example:
<?php
class Foo
{
  protected $title;
  public function __construct($title)
  {
    $this->title = $title;
  }
  public function __toString()
  {
    return $this->title;
  }
}
$array = [
  new Foo('foo'),
  new Foo('bar'),
  new Foo('qux')
];
echo implode('; ', $array);
?>
will output:
foo; bar; qux

Also quite handy in INSERT statements:
<?php
  // array containing data
  $array = array(
   "name" => "John",
   "surname" => "Doe",
   "email" => "j.doe@intelligence.gov"
  );
  // build query...
  $sql = "INSERT INTO table";
  // implode keys of $array...
  $sql .= " (`".implode("`, `", array_keys($array))."`)";
  // implode values of $array...
  $sql .= " VALUES ('".implode("', '", $array)."') ";
  // execute query...
  $result = mysql_query($sql) or die(mysql_error());
?>

If you want to implode an array of booleans, you will get a strange result:
<?php
var_dump(implode('',array(true, true, false, false, true)));
?>
Output:
string(3) "111"
TRUE became "1", FALSE became nothing.

It may be worth noting that if you accidentally call implode on a string rather than an array, you do NOT get your string back, you get NULL:
<?php
var_dump(implode(':', 'xxxxx'));
?>
returns
NULL
This threw me for a little while.

Even handier if you use the following:
<?php
$id_nums = array(1,6,12,18,24);
$id_nums = implode(", ", $id_nums);
        
$sqlquery = "Select name,email,phone from usertable where user_id IN ($id_nums)";
// $sqlquery becomes "Select name,email,phone from usertable where user_id IN (1,6,12,18,24)"
?>
Be sure to escape/sanitize/use prepared statements if you get the ids from users.

null values are imploded too. You can use array_filter() to sort out null values.
<?php
$ar = array("hello", null, "world");
print(implode(',', $ar)); // hello,,world
print(implode(',', array_filter($ar, function($v){ return $v !== null; }))); // hello,world
?>

It is possible for an array to have numeric values, as well as string values. Implode will convert all numeric array elements to strings.
<?php
$test=implode(["one",2,3,"four",5.67]);
echo $test;
//outputs: "one23four5.67"
?>