PHP include file包含一个文件奇怪的问题！
我面临一个奇怪的问题，包括 php 文件。让我向您展示代码：
// constants.php
$MYSQL_HOST_PORT = 'localhost:3306';
// functions.php
include 'constants.php';
function getVar() {
echo $MYSQL_HOST_PORT;
}
// doSth.php
include 'functions.php';
echo $MYSQL_HOST_PORT; // The variable is visible and echoed normally as expected!
echo getVar(); // The variable is not echoed! its "".
有什么想法吗？
I face a strange problem including php files. Let me show you the code:
// constants.php
$MYSQL_HOST_PORT = 'localhost:3306';
// functions.php
include 'constants.php';
function getVar() {
echo $MYSQL_HOST_PORT;
}
// doSth.php
include 'functions.php';
echo $MYSQL_HOST_PORT; // The variable is visible and echoed normally as expected!
echo getVar(); // The variable is not echoed! its "".
Any ideas ?
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评论（3）
其一，
echo getVar();中的echo永远不会打印任何内容，因为getVar不返回值。其次，如果您（出于某种原因）希望 getVar() 本身正常工作，则需要添加一个 global $MYSQL_HOST_PORT; 行，以使其查找
$MYSQL_HOST_PORT在全局范围内。For one, the
echoinecho getVar();won't ever print anything, becausegetVardoesn't return a value.Secondly, if you (for some reason) want
getVar()itself to work correctly, you need to add aglobal $MYSQL_HOST_PORT;line, to make it look for$MYSQL_HOST_PORTin the global scope.与其全局化
$MYSQL_HOST_PORT变量，为什么不简单地将其设为常量呢？如果包含了
constants.php，您就可以在任何地方引用MYSQL_HOST_PORT常量。正如 zerocrate 的回答中所示，这个问题是一个范围界定问题。
getVar()函数的封闭范围不包括$MYSQL_HOST_PORT。Rather than globalising the
$MYSQL_HOST_PORTvariable, why not simply make it a constant?Provided
constants.phpis included, you can reference theMYSQL_HOST_PORTconstant anywhere.As indicated in zerocrate's answer, the issue is a scoping one. The enclosed scope of the
getVar()function does not include$MYSQL_HOST_PORT.我发现错误的一件事是，使用
echo getVar();行，您没有从函数中获得返回值，因此您可以简单地编写getVar();靠它自己。One thing that I can see wrong is that with the line
echo getVar();you are not getting a return value from the function so you can simply writegetVar();by itself.