PHP loop control statement_PHP tutorial

There are several commonly used loop statements in PHP, while, do while, for(), and foreach. These four types are also commonly used loop statements in development. Friends in need can refer to this tutorial. Let’s talk about the usage of this statement one by one.

Foreach statement
The Foreach loop was introduced in php4.0 and can only be used for arrays. In php5, support for objects has been added. The syntax format of this statement is:
foreach(array_expression as $value)
statement;
or

The code is as follows

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代码如下	复制代码
Foreach(array_expression as $key => $value) statement; FOREACH ($array_variable as $value) {   [code to execute] } or FOREACH ($array_variable as $key => $value) {   [code to execute] }

Foreach(array_expression as $key => $value)

statement;

FOREACH ($array_variable as $value)

{

[code to execute]

代码如下	复制代码
$array1 = array(1,2,3,4,5); FOREACH ($array1 as $abc) {   print "new value is " . $abc*10 . " "; } 输出结果 new value is 10 new value is 20 new value is 30 new value is 40 new value is 50

}

or

FOREACH ($array_variable as $key => $value)

{

代码如下	复制代码
$s = array(array(1,2),array(3,4),array(5,6));  foreach( $s as $v => $_v )   {    foreach( $_v as $vc => $_vc )    {     echo $_vc[0],'|'.$_vc[1],' ';    //print_r($_vc);    }   }

[code to execute]

}

In both cases, multiple [code executions] will be killed that are equal to the number of array elements in $array_variable.

Let’s look at an example. Suppose we have the following code snippet:

The code is as follows

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代码如下	复制代码
/* example 1 */ for ($i = 1; $i <= 10; $i++) { echo $i; } /* example 2 */ for ($i = 1; ; $i++) { if ($i > 10) {         break;     }     echo $i; } /* example 3 */ $i = 1; for (; ; ) {     if ($i > 10) {         break;     }     echo $i;     $i++; } /* example 4 */ for ($i = 1, $j = 0; $i <= 10; $j += $i, print $i, $i++); ?>

$array1 = array(1,2,3,4,5); FOREACH ($array1 as $abc) { print "new value is " . $abc*10 . "
"; } Output results new value is 10 new value is 20 new value is 30 new value is 40 new value is 50

The above foreach loop goes through all 5 elements of the array $array1, printing out a statement containing 10 times the value of the array elements each time. The function of foreach is to traverse all the values ​​​​of the current array and assign them to $var Let’s look at an example of foreach operating on multidimensional data

The code is as follows	Copy code
$s = array(array(1,2),array(3,4),array(5,6)); foreach( $s as $v => $_v ) { foreach( $_v as $vc => $_vc ) { echo $_vc[0],'|'.$_vc[1],' '; //print_r($_vc); } }

For more details, please see: http://www.bKjia.c0m/phper/18/foreach-foreach.htm for statement The most based traversal

The code is as follows	Copy code
/* example 1 */<🎜> <🎜>for ($i = 1; $i <= 10; $i++) {<🎜> echo $i;<🎜> }<🎜> <🎜>/* example 2 */<🎜> <🎜>for ($i = 1; ; $i++) {<🎜> If ($i > 10) {          break; } echo $i; } /* example 3 */ $i = 1; for (; ; ) { If ($i > 10) {          break; } echo $i; $i++; } /* example 4 */ for ($i = 1, $j = 0; $i <= 10; $j += $i, print $i, $i++);<🎜> ?>

遍历数组

 代码如下

代码如下	复制代码
/* * This is an array with some data we want to modify * when running through the for loop. */ $people = Array( Array('name' => 'Kalle', 'salt' => 856412),         Array('name' => 'Pierre', 'salt' => 215863)         ); for($i = 0; $i < sizeof($people); ++$i) { $people[$i]['salt'] = rand(000000, 999999); } ?>

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/*

* This is an array with some data we want to modify

代码如下	复制代码
While (expression){ statement; }

* when running through the for loop.

*/

$people = Array(

        Array('name' => 'Kalle', 'salt' => 856412),         Array('name' => 'Pierre', 'salt' => 215863)

代码如下	复制代码
/* example 1 */ $i = 1; while ($i <= 10) { echo $i++; /* the printed value would be $i before the increment (post-increment) */ } /* example 2 */ $i = 1; while ($i <= 10): echo $i; $i++; endwhile; ?>

        );

for($i = 0; $i < sizeof($people); ++$i) {
    $people[$i]['salt'] = rand(000000, 999999); }
?>

下面再看

while 与do while

While循环是php中最简单的循环语句，他的语法格式是：

代码如下	复制代码
do { if ($i < 5) { echo "i is not big enough"; break; } $i *= $factor; if ($i < $minimum_limit) { break; } echo "i is ok"; /* process i */ } while (0); ?>

代码如下

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While (expression){ statement; } 当表达式expression的值为真时，将执行statement语句，执行结束后，再返回到expression表达式继续进行判断。直到表达式的值为假时，才跳出循环。  

 代码如下

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/* example 1 */<🎜> <🎜>$i = 1;<🎜> while ($i <= 10) {<🎜>     echo $i++;  /* the printed value would be<🎜>                    $i before the increment<🎜>                    (post-increment) */<🎜> }<🎜> <🎜>/* example 2 */<🎜> <🎜>$i = 1;<🎜> while ($i <= 10):<🎜>     echo $i;<🎜>     $i++;<🎜> endwhile;<🎜> ?> Do…While语句 While语句还有一种形式的表示，Do…While.语法为： Do{ statement; }While(expression); 两者的区别在于：Do…While语句要比While语句多循环一次。 当While表达式的值为假时，While循环直接跳出当前循环，而Do…While语句则是先执行一遍程序块，然后再对表达式进行判断。 实例

代码如下

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do {<🎜>     if ($i < 5) {<🎜>         echo "i is not big enough";<🎜>         break;<🎜>     }<🎜>     $i *= $factor;<🎜>     if ($i < $minimum_limit) {<🎜>         break;<🎜>     }<🎜>    echo "i is ok";<🎜> <🎜>    /* process i */<🎜> <🎜>} while (0);<🎜> ?> http://www.bkjia.com/PHPjc/629268.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/629268.htmlTechArticleThere are several commonly used loop statements in php, while, do while, for(), foreach. This is also a loop statement commonly used in development. Friends in need can refer to this...