php a tag jumps to the previous page

In web development, it is often necessary to use a tags in pages to jump to other pages or locations. But sometimes, it is necessary to implement a function that returns to the previous page after clicking the a tag, which is equivalent to the function of the browser's "back" button. So, how should we implement this function when using PHP?

First, you need to know how to get the URL of the current page in PHP. You can use the $_SERVER['PHP_SELF'] function to get the URL of the current page. At the same time, you can also use the $_SERVER['HTTP_REFERER'] function to obtain the reference page URL of the current page.

Specifically, $_SERVER['PHP_SELF'] returns the URL address of the current page, while $_SERVER['HTTP_REFERER'] returns The URL address of the reference page of the current page, that is, the page from which you jump to the current page.

With the help of these two functions, you can realize the function of jumping to the previous page by clicking on the a tag. The following are the specific steps:

1. Use $_SERVER['HTTP_REFERER'] to get the referring page URL of the current page.
2. Save the obtained URL value in a PHP variable.
3. Use the a tag to jump and set the href attribute to the saved reference page URL.
4. When you click the a tag, the program will jump to the saved reference page URL, thus achieving the effect of returning to the previous page.

The following is a sample code that demonstrates how to use PHP to implement the function of a tag jumping to the previous page:

<?php
// 获取当前页面的引用页 URL
$prevPageUrl = $_SERVER['HTTP_REFERER'];

// 输出一个 a 标签，点击后跳转到前一页
echo '<a href="' . $prevPageUrl . '">返回前一页</a>';

// 使用 header 函数实现自动跳转到前一页
header('Location: ' . $prevPageUrl);
exit;
?>

In this example, two methods are used to achieve it a label jumps to the previous page. First, an ordinary a tag is used. When the user clicks the tag, the program will jump to the saved reference page URL, that is, the previous page. In addition, the header function is also used to automatically jump to the previous page. This method can directly jump to PHP without the need to use the a tag.

It should be noted that there are some restrictions on using the $_SERVER['HTTP_REFERER'] function. Because this function returns the URL of the previous page, which is not necessarily legal or correct, and some browsers may disable this function, you need to take these restrictions into consideration when using it.

In short, it is not difficult to implement a tag to jump to the previous page in PHP development. You only need to get the reference page URL of the current page, and then set the href attribute in the a tag and set it as a reference. Page URL, you can achieve this function. Of course, you can also use the header function to automatically jump to the previous page. You only need to pass the previous page URL as a parameter to the header function.

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