PHP array learning talks about several methods of outputting arrays

In the previous articles "How to create and initialize a one-dimensional array in PHP array learning (detailed code explanation)" and "A brief analysis of the creation method of a two-dimensional array in PHP array learning" In this article, we introduce the definition method of one-dimensional array and two-dimensional array through code examples, which is simple and easy to understand.

Now that the array is created and initialized, after performing some operations, it needs to output and print out the operation results. So how to output PHP array? The following article will introduce to you several methods of array output: print_r(), var_dump(), echo/print. (Attachment: PHP function array array function video explanation)

1. Use print_r() to output the array

The print_r() function is used to print variables in a more understandable form. The print_r() function can output the contents and structure of the entire array, and the keys and elements will be displayed in a certain format.

<?php
header("Content-type:text/html;charset=utf-8");
$array = array
(
    array("姓名"=>"张三","年龄"=>25,"性别"=>"男"),
    array("姓名"=>"李四","年龄"=>21,"性别"=>"男"),
    array("姓名"=>"娜娜","年龄"=>22,"性别"=>"女")
);
 print_r($array);
?>

Output result:

Array ( [0] => Array ( [姓名] => 张三 [年龄] => 25 [性别] => 男 ) [1] => Array ( [姓名] => 李四 [年龄] => 21 [性别] => 男 ) [2] => Array ( [姓名] => 娜娜 [年龄] => 22 [性别] => 女 ) )

Do you feel that the output result is too long and you do not use reading. You can add a piece of code "echo '

';" before the print_r() output statement: </p><pre class='brush:php;toolbar:false;'><?php
header("Content-type:text/html;charset=utf-8");
$array = array
(
    array("姓名"=>"张三","年龄"=>25,"性别"=>"男"),
    array("姓名"=>"李四","年龄"=>21,"性别"=>"男"),
    array("姓名"=>"娜娜","年龄"=>22,"性别"=>"女")
);
echo &#39;<pre class="brush:php;toolbar:false">&#39;;
 print_r($array);
?>

The output result is more conducive to reading, the output result:

2. Use var_dump() to output the array

Similar to the print_r() function, the var_dump() function can also dump the entire array Data content and structure are output. However, var_dump() is more powerful than print_r(). It can print multiple variables at the same time and give the type information of the variables.

The var_dump() function can output relevant information (type and value) of variables. When outputting an array, the array will recursively expand the values ​​and display its structure through indentation.

<?php
header("Content-type:text/html;charset=utf-8");
$array = array
(
    array("姓名"=>"张三","年龄"=>25,"性别"=>"男"),
    array("姓名"=>"李四","年龄"=>21,"性别"=>"男"),
    array("姓名"=>"娜娜","年龄"=>22,"性别"=>"女")
);
 var_dump($array);
?>

Output result:

Description:

print_r() and var_dump() functions are generally used for debugging programs, more In many cases, echo is used to output specific array unit values.

3. Use echo/print to output an array

echo() is used to output one or more strings.

Strictly speaking, echo is not a function, it is actually a language structure; therefore, it is not necessary to use parentheses to indicate parameters, single quotes or double quotes can also be used.

However, if you pass more than one argument to echo(), you cannot use parentheses because a parsing error will be generated.

print() and echo() are somewhat similar (it is actually a language construct), but the difference is that echo can accept multiple parameters and has no return value, while print() can only Accepts one parameter and returns a value.

When using echo/print for array output, only a certain element in an array can be output. Let's take a closer look through code examples:

<?php
header("Content-type:text/html;charset=utf-8");
$array= array("香蕉","苹果","梨子","橙子","橘子","榴莲");
//输出语句
echo &#39;$array[0] = &#39;.$array[0].&#39;<br>&#39;;
echo &#39;$array[1] = &#39;.$array[1].&#39;<br>&#39;;
echo &#39;$array[2] = &#39;.$array[2].&#39;<br>&#39;;

print &#39;$array[3] = &#39;.$array[3].&#39;<br>&#39;;
print &#39;$array[4] = &#39;.$array[4].&#39;<br>&#39;;
print &#39;$array[5] = &#39;.$array[5].&#39;<br>&#39;;
?>

Output:

$array[0] = 香蕉
$array[1] = 苹果
$array[2] = 梨子
$array[3] = 橙子
$array[4] = 橘子
$array[5] = 榴莲

Statements in the form of "$array variable name[subscript]" are used to access arrays of elements to determine the elements that need to be output. For example, in the above example, "$array[0]" is to access the first element in the array (the subscript of the index array starts from zero), so "echo $array[0 ]" statement can output "banana".

If you want to output all the elements in the array, you need to use a loop statement to traverse the array and output the elements in the array one by one.

Let’s take the foreach statement as an example to see in detail how to loop through the array and output all the elements in the array: (Video tutorial attached: foreach loop)

<?php
header("Content-type:text/html;charset=utf-8");
$array= array("香蕉","苹果","梨子","橙子","橘子","榴莲");
foreach ($array as $val){  // 遍历数组
	//输出数组元素
    echo $val."<br>";  
}

?>

Output results:

香蕉
苹果
梨子
橙子
橘子
榴莲

Recommendation: 《2021 PHP interview questions summary (collection)》《php video tutorial》

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