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This article mainly explains "how to catch error prompts by php". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn "how to catch error tips by php".

Php captures error prompts: 1, through "error_reporting (E_ALL);" output all errors; 2, use "try...catch" to catch exceptions; 3, use set_error_handler () function to host error handlers.

This article operating environment: windows7 system, PHP7.1 version, DELL G3 computer

How does php catch error messages?

Php exception handling captures error collation

There are three types of error reports for PHP:

1. Error, syntax parsing error, fatal error

2. Warning

3. Pay attention

Consequences:

Error-> fatal error will terminate the execution of the downloaded program. If the syntax is wrong, PHP will not be executed at all.

Warning-> he will not terminate the operation, but it will affect the results.

Note that-> will not terminate the execution and will not affect the result.

In order to give users a better experience, we shield the output of all errors, which is output, not display. But in this case, the administrator will not see the error. No errors are displayed on the page

Error, and generate a log of the error, which is provided to the administrator to view.

Error_reporting (~ E_ALL) blocks all the output and, of course, the administrator can't see it. I don't want to block all the output. I just want to block all the displays.

Ini_set ('display_errors','off'); means that all incorrect displays on the page are blocked, but the incorrect output is not blocked.

Ini_set ('log_errors','on'); / enable log writing function ini_set (' error_log','myerror.log'); / / location of log storage ini_set ('display_errors','off'); / / screen page display error_reporting (E_ALL); / / output all errors echo 123; echo $log / / this will show a note indicating that the variable echo date () is not declared / / warning, no parameter echo dae () was passed; / / fatal error, this function echo 123 cannot be found

Exception:

In the PHP language, all exceptions have to be thrown by themselves, unlike languages such as JAVA, which are rarely seen in PHP source code.

One of the reasons.

Exceptions and errors:

Exception refers to the situation that does not conform to the expected situation in the operation of the program and is different from the normal process. The error belongs to its own problem, which is caused by an illegal syntax or environmental problem.

Failed to check for settings that cannot be run.

Since php started out without exception handling, it was later imitated in order to enter enterprise development. When PHP encounters abnormal code, in most cases, it throws an error directly instead of

It's abnormal.

Php can use try...catch to catch exceptions only after you throw an exception (in general, some exceptions can be caught automatically).

Exceptions are typically used in the following scenarios in php:

1. Pessimistic prediction of the program: if you think your code can't handle all kinds of foreseeable and unpredictable situations one by one.

2. The need of the program and attention to the business: if there is a high requirement for data consistency, try...catch can be used to minimize the logical interruption caused by the exception and be remedied.

After processing, the integrity of the business logic is not affected.

3. Language-level robustness requirements: through precise control of the runtime process, when the program is interrupted, use try...catch to reduce the scope of possible errors, catch exceptions and do it in time.

Come up with the corresponding remedy.

Error in PHP:

An error is a situation that makes the script run improperly.

The main error levels in php are as follows:

Deprecated: the lowest level of error, meaning "not recommended, not recommended". For example, regular functions of the ereg family are used in php 5. Such errors are generally caused by the use of unrecommended and outdated functions or syntax. It does not affect the normal operation of the program, but it is recommended to correct it.

Notice: generally speaking, there is an inappropriate place in the grammar. This error will be reported if you use a variable but are not defined. Does not affect the normal process of the program.

Warning: a high-level error that occurs only when there is a very inappropriate situation in the syntax, such as a mismatch in function parameters. Will result in not getting the expected results, and the code needs to be modified.

Fetal error: a fatal error that directly causes the program to stop running. This kind of error must be corrected.

Prase error: syntax parsing errors, all of which are run-time errors that are thrown before running.

Custom error handlers:

You can use the set_error_handler () function to host the error handler, and you can customize the error handling flow.

If you want to unhost, you can use restore_error_handler () in the same page to unhost; if you want to throw an error yourself, you can use the

Trigger_error () function.

At this point, I believe you have a deeper understanding of "php how to catch error prompts". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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