使用include和require的區別實例分析

網路上太多關於PHP中include與require區別。然而事實真的如此嗎，今天我們就透過一個具體的實例來簡單分析驗證下

先編輯command.php檔案

echo 'hello'.PHP_EOL;

然後編輯console.php檔案

for($i=1;$i<=3;++$i){
	require &#39;command1.php&#39;;
}

原本想要包含並執行這個echo，沒想到寫錯了檔名，如果是require，會報出這樣的錯誤：

Warning: require(command1.php): failed to open stream: No such file or directory in console.php on line 4

Fatal error: require(): Failed opening required 'command1.php' (include_path='.') in console.php on line 4
PHP Warning: require(command1.php): failed to open stream: No such file or directory in console.php on line 4
PHP Fatal error: require(): Failed opening required 'command1.php' (include_path='.') in console.php on line 4

如果把require改為include

for($i=1;$i<=3;++$i){
	include &#39;command1.php&#39;;
}

會報出這樣的錯誤：

Warning: include(command1.php): failed to open stream: No such file or directory in console.php on line 4

Warning: include(): Failed opening 'command1.php' for inclusion (include_path='.') in console.php on line 4

Warning: include(command1.php): failed to open stream: No such file or directory in console.php on line 4

Warning: include(): Failed opening 'command1.php' for inclusion (include_path='.') in console.php on line 4

Warning: include(command1.php): failed to open stream: No such file or directory in console.php on line 4

Warning: include(): Failed opening 'command1.php' for inclusion (include_path='.') in console.php on line 4
PHP Warning: include(command1.php): failed to open stream: No such file or directory in console.php on line 4
PHP Warning: include(): Failed opening 'command1.php' for inclusion (include_path='.') in console.php on line 4
PHP Warning: include(command1.php): failed to open stream: No such file or directory in console.php on line 4
PHP Warning: include(): Failed opening 'command1.php' for inclusion (include_path='.') in console.php on line 4
PHP Warning: include(command1.php): failed to open stream: No such file or directory in console.php on line 4
PHP Warning: include(): Failed opening 'command1.php' for inclusion (include_path='.') in console.php on line 4

如果使用require_once或include_once，只要包含路徑正確，那麼循環#只執行一次。

總結：

使用require，如果檔案沒有包含成功，就會報出一個fatal error，整個程式就中止了。

使用include，如果檔案沒有包含成功，就會報出一個普通的warning，之後的程式碼仍會執行。

如果你的網路程式使用了MVC這種對檔案包含強依賴的設計方法，請使用require_once。

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