[英]How do I check whether an environment variable is set in PHP?
In PHP, how do I test whether an environment variable is set? 在PHP中,如何测试是否设置了环境变量? I would like behavior like this:
我想这样的行为:
// Assuming MYVAR isn't defined yet.
isset(MYVAR); // returns false
putenv("MYVAR=foobar");
isset(MYVAR); // returns true
getenv()
returns false
if the environment variable is not set. 如果未设置环境变量,
getenv()
将返回false
。 The following code will work: 以下代码将起作用:
// Assuming MYVAR isn't defined yet.
getenv("MYVAR") !== false; // returns false
putenv("MYVAR=foobar");
getenv("MYVAR") !== false; // returns true
Be sure to use the strict comparison operator ( !==
) because getenv()
normally returns a string that could be cast as a boolean. 一定要使用严格比较运算符(
!==
),因为getenv()
通常返回一个可以作为布尔值转换的字符串。
This is what you need 这就是你需要的
$var = getenv(MYVAR)
if(isset($var)) {
} else {
}
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