How to use echo to display array in php

In PHP programming, we often need to display array data on a web page or output it as a log. At this time, we can use the echo statement to output each element of the array to the web page or log. Here are some commonly used methods of displaying arrays.

Method 1: Use for loop to output array

We can use for loop to traverse each element in the array, and then use the echo statement to output the value. The sample code is as follows:

$arr = array('apple', 'banana', 'orange', 'lemon');
for ($i=0; $i<count($arr); $i++) {
    echo $arr[$i]."<br/>";
}

In the above code, we first define an array $arr containing 4 elements, and then use a for loop to traverse the array, starting from 0 and looping to the length of the array, that is, count( $arr)-1. In the loop body, we output each element in the array to the web page through the echo statement, and add an HTML newline symbol "
" after each element to make the output text easier Read and understand.

Method 2: Use foreach loop to output array

In PHP programming, we can also use foreach loop to traverse the array. This method can more conveniently access the elements in the array. The sample code is as follows:

$arr = array('apple', 'banana', 'orange', 'lemon');
foreach ($arr as $value) {
    echo $value."<br/>";
}

In the above code, we use a foreach loop to traverse the array $arr. Each loop takes out an element in the array and assigns it to the variable $value, and then uses the echo statement to This element is output to the web page. Unlike the for loop, the foreach loop does not need to explicitly use the array subscript to access the elements, because it has assigned the value of each element to the variable $value, and you can use the variable directly.

Method 3: Use the print_r or var_dump function to output the array

In PHP programming, we can also use the print_r or var_dump function to output the structure and content of the array to the web page or log. The main difference between these two functions is that the print_r function only displays the values ​​in the array, while the var_dump function displays not only the values ​​in the array, but also their data type and length. The sample code is as follows:

$arr = array('apple', 'banana', 'orange', 'lemon');
echo "<pre class="brush:php;toolbar:false">";
print_r($arr);
echo "

"; echo "

";
var_dump($arr);
echo "

";

In the above code, we first use the print_r and var_dump functions to output the structure and content of the array $arr to the web page. In order to make the output content easier to read and understand, we include it in a

 tag in HTML, which can display text content in a fixed-width font and support automatic line wrapping. 

The above are three commonly used methods for displaying arrays in PHP. Choosing the appropriate method according to the actual situation can improve the readability and maintainability of the code, and help us locate and fix problems faster. 
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