Can php use for to write arrays?

PHP cannot use for to write arrays, it can only traverse arrays. The for loop is a way to traverse an array that can be used in almost all languages, and the PHP language is no exception.

The operating environment of this tutorial: Windows 10 system, PHP8.1.3 version, Dell G3 computer.

The for loop in php can traverse the array.

The for loop is a way to traverse an array that can be used in almost all languages, and the PHP language is no exception.

1. Structural analysis of the for loop statement

The for loop will pre-define the variables that control the number of loops in the for statement, so the for loop statement can perform loop operations according to the known number of loops. , suitable for situations where you know exactly how many times the script needs to be run.

The syntax format of the for loop is as follows:

for (初始化语句; 循环条件; 变量更新--自增或自减) {
    语句块;  
}

The for loop statement can be broken down into four parts: (the three expressions in ) and the "statement block" in {}, Let’s analyze it below.

Statement analysis:

Initialization statement (expression 1): mainly initializes a variable value, used to set a counter, that is, the value at the beginning of the loop; this statement is only used in the first Executed once in the loop, it will not be executed again in the future.

Loop condition (expression 2): The restriction condition of loop execution, used to control whether to execute the code in the loop body; if the condition is TRUE, the loop continues, if the condition is FALSE, the loop ends immediately Exit the loop.

Variable update (expression 3): An expression with an auto-increment or auto-decrement operation. Each time the loop is executed, the value of the counter is immediately modified so that the loop condition gradually becomes "not true." ".

Statement block: Several codes that need to be executed when the condition is judged to be true.

Is the above description a bit convoluted? Let’s take a look at the execution flow chart of the for loop statement to understand the execution process of the for loop more intuitively:

2. for loop Statement traversal array

Let’s first look at how to traverse through code examples, and then learn more about it by analyzing the code.

<?php header("Content-type:text/html;charset=utf-8");
$array= array("香蕉","苹果","梨子","橙子","橘子","榴莲");
var_dump($array);
echo "for循环遍历输出：<br/><br>";
for ($i=0; $i ";
}
?>

Output:

Code analysis:

The initialization statement is $i=0: the array of the example is an index array, the array The subscript starts from 0 by default, so the value at the beginning of the loop must be 0.

Loop condition $i

Variable update $i: After each loop, the variable $i automatically increases by 1 until $i = array length. Because $i exceeds the index range, the loop condition is not true, and then the loop exits.

echo $array[$i] . "
": Each time it loops, the array elements are output based on the $i value--the array subscript.

Note: Using a for loop to traverse an array will not change the internal pointer of the array.

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