What is exception handling in PHP? How to use try-catch in exception handling?

The previous article introduced you to "How to use advanced syntax and try-catch in PHP". This article continues to introduce to you what is exception handling in PHP? How do we use try-catch in exception handling? It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

Exception handling:

In life:

Plan A, Plan B

In the code:The code is executed according to normal logic. If an exception occurs, another prepared plan is executed.

try catch:Mapping In the code, try is to try to execute a certain block of code, and if an exception occurs, you need to manually throw an exception (throw). After the exception is thrown, it will be caught by catch.

[Note] try-catch is a structure, a try must correspond to at least one catch

[Note] No code can be added between try and catch

try-catch fixed format:

try {
} catch () {
}

Let’s take the code as an example and create a new file. The code is as follows:

<?php
try {
  echo &#39;你是一树一树的花开<br />&#39;;
  echo &#39;是燕在梁间呢喃<br />&#39;;
  echo &#39;你是爱，是暖，是希望<br />&#39;;
} catch (Exception $e) {
}
echo &#39;你是人间的四月天&#39;;

The execution results are as follows:

We will find that the results are output in the normal order. If there is no exception, catch will not be executed directly. If there is an exception, then we will throw the exception manually. , throw an exception through throw. Let's take the code as an example:

<?php
try {
  echo &#39;你是一树一树的花开<br />&#39;;
  echo &#39;是燕在梁间呢喃<br />&#39;;
  throw new Exception(&#39;出现错误了&#39;,10);
  echo &#39;你是爱，是暖，是希望<br />&#39;;
} catch (Exception $e) {
}
echo &#39;你是人间的四月天&#39;;

The execution result is as follows:

We will find that the code directly skips the first Three sentences;

So our execution process is: the program runs the code in the try structure normally. If an exception is thrown in the try, the code after the exception thrown in the try will not be executed again, then The code in catch will be executed and then continue to execute downwards. If no exception is thrown, after the code in try is executed, the program will continue to execute Exception

In fact, when we throw this exception, catch The exception we throw can be captured inside. If we want to capture the error message, we can use getMessage() in echo. The code is as follows:

catch (Exception $e) {
  echo $e->getMessage();
}

The execution result is as follows:

The official exception handling class is the base class of all exception classes

getMessage: Get the exception message

getCode: Get the exception code

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