What is the difference between getenv and server in php

The difference between getenv and server in php: 1. getenv can obtain the system environment variables, the syntax is "string getenv(string varname)", and "$_SERVER" is the server super global variable array; 2. getenv PHP running in IIS isapi mode is not supported, "$_SERVER" is supported.

The operating environment of this article: Windows 10 system, PHP version 8.1, Dell G3 computer

What is the difference between getenv and server in php

The difference in usage between getenv() and $_SERVER in PHP:

getenv obtains the system environment variables, and the format of the environment variables is name=value.

Syntax:

string getenv(string varname);

Return value: String function type: PHP system function

Content description

If the environment variable varname is obtained correctly, the variable will be returned value, returns false on failure.

The following example can get the URL of the machine where the user's browser is located

$ip = getenv(“REMOTE_ADDR”);
?>

$_SERVER is the server super global variable array. Use $_SERVER['REMOTE_ADDR'] to also get the IP address of the client. .

The difference between the two is that getenv does not support PHP running in IIS isapi mode.

Expand knowledge

Solution that PHP cannot obtain the ip address` functiongetenv("REMOTE_ADDR") The difference from $_SERVER['REMOTE_ADDR']

I recently used PHP to help a friend write a page for voting. Everything went smoothly. After installing it, I found: The visitor’s IP address is missing. It can be recorded (it failed to obtain the IP address), which is strange. The local test was all fine. Is it possible that the local computer is different from the server? I immediately opened a space and tested it. Everything is still normal. After troubleshooting every problem, I learned that the other party was running IIS under Windows, while my own tests were all on Apache. This was probably the reason.

Replace the function immediately: replace the original ip address acquisition function "getenv("REMOTE_ADDR")" with "$_SERVER['REMOTE_ADDR']", overwrite Update, check the database again, the IP address has been successfully recorded, done.

Since we encounter this problem again, let’s record it: the difference between getenv("REMOTE_ADDR") and $_SERVER['REMOTE_ADDR'] in PHP to obtain the IP address of the visitor (*** end). In fact, through this incident, it has become very clear. The getenv("REMOTE_ADDR") function can successfully obtain the IP address in Apache, but in iis, it has no effect at all. The $_SERVER['REMOTE_ADDR'] function can successfully obtain the visitor's IP address in apache, but in iis Also valid below.

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