PHP loop statement
What is a loop statement?
In many practical problems There are many repetitive operations with regularity, so certain statements need to be executed repeatedly in the program. A group of statements that are executed repeatedly is called a loop body. Whether it can continue to be repeated determines the termination condition of the loop. A loop structure is a process structure that repeatedly executes a certain program under certain conditions. The repeatedly executed program is called a loop body. A loop statement is composed of two parts: the loop body and the loop's termination condition.
Simply put, when you write code, you often need to have the same blocks of code run over and over again. We can use loop statements in our code to accomplish this task.
In PHP, the following loop statements are provided:
1. while - As long as the specified condition is true, the code block will be executed in a loop
2. do...while - first execute the code block once, and then repeat the loop when the specified condition is true
3. for - loop the specified number of times to execute the code block
4. foreach - Loop the code block based on each element in the array
Loop and execute the code block a specified number of times, or when the specified condition is true Loop through a block of code.
while loop
The while loop will execute the code block repeatedly until the specified condition is not true.
Syntax:
while (条件)
{
要执行的代码;
}The following example first sets the value of variable i to 1 ($i=1;).
Then, as long as i is less than or equal to 5, the while loop will continue to run. Each time the loop runs, i will be incremented by 1:
<html>
<body>
<?php
$i=1;
while($i<=5)
{
echo "The number is " . $i . "<br>";
$i++;
}
?>
</body>
</html>Run result:
The number is 1 The number is 2 The number is 3 The number is 4 The number is 5
do...while statement
The do...while statement will execute the code at least once, then check the condition, and repeat the loop as long as the condition is true.
Syntax:
do
{
要执行的代码;
}
while (条件);The following example first sets the value of variable i to 1 ($i=1;).
Then, start the do...while loop. The loop increments the value of variable i by 1 and then outputs it. First check the condition (i is less than or equal to 5), as long as i is less than or equal to 5, the loop will continue to run:
<html>
<body>
<?php
$i=1;
do
{
$i++;
echo "The number is " . $i . "<br>";
}
while ($i<=5);
?>
</body>
</html>Running result:
The number is 2 The number is 3 The number is 4 The number is 5 The number is 6
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