How to set the life cycle of cookie PHP

In website development, cookies are a very commonly used form of data storage. A cookie is a text file consisting of a name, value and other optional attributes that can be saved on the user's computer. Among them, one of the most important attributes is to specify the cookie's life cycle (expires), that is, how long the cookie is stored on the client computer. In PHP, you can use the setcookie() function to set cookies, including setting the cookie's name, value, expiration time and other attributes. Below, this article will introduce in detail how to set the cookie life cycle in PHP.

1. setcookie() function

The setcookie() function is a function used to set cookies in PHP. Its syntax is as follows:

setcookie(name,value, expire,path,domain,secure,httponly);

Among them, the meaning of the parameters is as follows:

• name: The name of the cookie, which must be set.
• value: The value of the cookie, which can be empty.
• expire: cookie life cycle, specified in the form of Unix timestamp.
• path: Specify the path under which the cookie is valid. The default is valid under the entire domain name.
• domain: Specify the domain name under which the cookie is valid. The default is the current domain name.
• secure: Whether to transmit this cookie only through HTTPS protocol, 0 or 1, default is 0.
• httponly: Whether to restrict this cookie to only be accessed through HTTP or HTTPS protocol, 0 or 1, default is 0.

Among them, the expire parameter is the focus.

2. Cookie life cycle

The cookie life cycle can be understood as the validity period of the cookie on the client computer. In PHP, we can use the expire parameter to specify the life cycle of the cookie on the client computer. The value of the expire parameter is an integer value represented as a Unix timestamp. The timestamp is the number of seconds relative to 00:00:00GMT on January 1, 1970, so we can get the expiration time through calculation.

Now, let’s look at an example. For example, we want to set a cookie named "mycookie" and have it expire 60 minutes from the current time. Then you can do this:

$expire=time()+60*60; //设置生命周期为60分钟
setcookie("mycookie", "test", $expire);

In this example, we first get the timestamp of the current time (implemented with the time() function), and then add 60 minutes (ie 3600 seconds) to get a 60-minute timestamp after. Finally, we pass this timestamp to the third parameter $expire of the setcookie() function, thereby specifying that the life cycle of "mycookie" is 60 minutes.

If we want not to set the expiration time, that is, let the cookie be automatically deleted when the browser is closed, then we can set the expire parameter to 0, as shown below:

setcookie("mycookie", "test", 0);

In addition, if we want To delete a cookie immediately, you can set its life cycle to a timestamp in the past, as shown below:

setcookie("mycookie", "", time()-3600);

In this example, we set the life cycle of "mycookie" to 60 minutes of the current time before, the cookie is deleted immediately.

3. Practical Application

In practical applications, we can set the cookie life cycle according to specific needs. For example, if we want to remember the user's login status, we can save the user's user name and password when logging in to a cookie, and set the life cycle to a number of days, a number of hours, a number of minutes, etc. In this way, even if the user closes the browser or restarts the computer, the user does not need to log in again as long as the cookie has not expired.

Now, let’s look at a practical example. Suppose we have a login page. After the user enters the username and password, they can check the "Remember Password" option. If checked, the username and password will be saved in cookies so that the user does not need to re-enter them the next time they log in. user name and password. The specific implementation code is as follows:

<?php
if(isset($_POST[&#39;username&#39;]) && isset($_POST[&#39;password&#39;])){
    $username = $_POST[&#39;username&#39;];
    $password = $_POST[&#39;password&#39;];
    if(isset($_POST[&#39;remember&#39;])){
        //如果勾选“记住密码”，则设置cookie生命周期为7天
        setcookie(&#39;username&#39;, $username, time()+3600*24*7);
        setcookie(&#39;password&#39;, $password, time()+3600*24*7);
    }else{
        //如果未勾选“记住密码”，则不设置生命周期，即在浏览器关闭时自动删除cookie
        setcookie(&#39;username&#39;, $username);
        setcookie(&#39;password&#39;, $password);
    }
    //进行登录验证，此处省略......
}
?>

<form method="post" action="">
    <label>用户名：<input type="text" name="username"></label><br>
    <label>密码：<input type="password" name="password"></label><br>
    <label><input type="checkbox" name="remember">记住密码</label><br>
    <input type="submit" value="登录">
</form>

In this example, if the user checks the "Remember Password" option, the user name and password are saved in cookies and the life cycle is set to 7 days. If the user does not check the "Remember Password" option, no life cycle is set, that is, the cookie is automatically deleted when the browser is closed. In this way, the next time the user opens the login page, they can see the username and password saved during the last login (if the cookie has not expired), making it easier for the user to log in quickly.

4. Summary

In PHP, the life cycle of cookies can be easily set through the setcookie() function. We can set the cookie life cycle according to specific needs to achieve various data storage needs, such as remembering user login status, saving user preferences, etc. At the same time, we also need to pay attention to the calculation based on the timestamp when setting the cookie life cycle to ensure that the correct life cycle is set.

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