什么是 PHP 中的异常处理?
异常是在程序执行期间出现的问题。在程序执行过程中,当发生异常时,语句后面的代码将不会执行,PHP 将尝试查找第一个匹配的 catch 块。如果未捕获异常,则会发出带有“未捕获异常”的 PHP 致命错误。
语法
try { print "this is our try block"; throw new Exception(); }catch (Exception $e) { print "something went wrong, caught yah! n"; }finally { print "this part is always executed"; }
示例
<?php function printdata($data) { try { //If var is six then only if will be executed if($data == 6) { // If var is zero then only exception is thrown throw new Exception('Number is six.'); echo "
After throw (It will never be executed)"; } } // When Exception has been thrown by try block catch(Exception $e){ echo "
Exception Caught", $e->getMessage(); } //this block code will always executed. finally{ echo "
Final block will be always executed"; } } // Exception will not be rised here printdata(0); // Exception will be rised printdata(6); ?>
输出
Final block will be always executed Exception CaughtNumber is six. Final block will be always executed
备注
要处理异常,程序代码必须在 try 块内。每个 try 必须至少有一个相应的 catch 块。可以使用多个 catch 块来捕获不同类的异常。
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