A brief analysis of how to use the array function in php

PHP is a scripting language widely used in Web development. It is good at processing HTTP requests and generating multimedia formats such as dynamic pages, images, and PDFs. In PHP, array is a very commonly used data type. The array function is a built-in function library for creating and manipulating arrays. This article will introduce the basic usage of php array function.

1. Create an array

Array is one of the most commonly used data structures in PHP. We can use the array function to create an array. The following is a common way to create an array:

//直接声明
$colors = array("red", "green", "blue");

//使用键值对
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");

//空数组
$emptyArray = array();

2. Access the array

We have created the array, now let’s access the elements in it. In PHP, you can use array subscripts to access values ​​within an array. The subscript can be a number or a string.

//访问数字下标
$colors = array("red", "green", "blue");
echo $colors[1];  //输出 "green"

//访问字符串下标
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
echo $age["Ben"];  //输出 "37"

3. Modify and delete arrays

The next step is how to modify and delete array elements.

//修改数组元素
$colors = array("red", "green", "blue");
$colors[0] = "yellow";   //将第一个元素从"red"改为"yellow"
print_r($colors);   //输出 Array ( [0] => yellow [1] => green [2] => blue )

//删除数组元素
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
unset($age["Ben"]);   //删除元素"Ben"
print_r($age);   //输出 Array ( [Peter] => 35 [Joe] => 43 )

4. Array traversal

When we need to operate on all elements in the array, we need to use a loop structure to traverse the array. PHP provides a variety of ways to traverse arrays, including for loops, foreach loops, while loops, etc.

//for循环遍历数组
$colors = array("red", "green", "blue");
for ($i = 0; $i < count($colors); $i++) {
    echo $colors[$i] . "\n";
}

//foreach循环遍历数组
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
foreach($age as $x => $x_value) {
    echo "Key=" . $x . ", Value=" . $x_value;
}

//while循环遍历数组
$colors = array("red", "green", "blue");
$i = 0;
while($i < count($colors)) {
    echo $colors[$i] . "\n";
    $i++;
}

5. Array sorting

In PHP, we can use the built-in sort() function to sort the array. By default, the sort() function sorts the array in ascending order. If you need to sort in descending order, you can use the rsort() function.

//使用sort()函数升序排列数组
$numbers = array(4, 2, 8, 5, 1);
sort($numbers);
print_r($numbers);   //输出 Array ( [0] => 1 [1] => 2 [2] => 4 [3] => 5 [4] => 8 )

//使用rsort()函数降序排列数组
$numbers = array(4, 2, 8, 5, 1);
rsort($numbers);
print_r($numbers);   //输出 Array ( [0] => 8 [1] => 5 [2] => 4 [3] => 2 [4] => 1 )

6. Array merging

In PHP, we can use the built-in array_merge() function to merge multiple arrays into one array.

//使用array_merge()函数合并数组
$a1=array("red","green");
$a2=array("blue","yellow");
print_r(array_merge($a1,$a2));   //输出 Array ( [0] => red [1] => green [2] => blue [3] => yellow )

7. Array search

In PHP, we can use the in_array() function to determine whether an element exists in an array. This function returns true or false.

//使用in_array()函数查找数组
$colors = array("red", "green", "blue");
if(in_array("red",$colors)) {
    echo "found!";
} else {
    echo "not found!";
}

Generally speaking, the array function in PHP provides various practical methods to operate arrays, which can make us more convenient for web development. Proficient in these basic usages, you can get twice the result with half the effort in development.

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