1. Notices
These are relatively small and not serious errors, such as accessing an undefined variable. Usually, such errors are not prompted to the user, but sometimes these errors will affect the results of the operation.
2. Warnings
This is a slightly more serious error, such as trying to include() a file that does not exist. Such an error message will be prompted to the user, but will not cause the program to terminate.
3. Fatal errors
These are serious errors. For example, if you want to initialize an object of a class that does not exist at all, or call a function that does not exist, these errors will cause the program to stop running. PHP These errors will also be displayed to the user.
Different error types include:
E_ERROR: Usually displayed, it can also interrupt program execution.
E_WARNING: Usually displayed, but will not interrupt program execution.
E_NOTICE: A code error that occurs when the script is running normally.
E_PARSE: Syntax parsing error.
E_CORE_ERROR: Fatal error that occurred during PHP startup.
E_CORE_WARNING: Report non-fatal errors that occur when PHP starts.
E_COMPILE_ERROR: Fatal error that occurs during compilation, indicating errors in the script.
E_USER_ERROR: User-generated error message.
E_USER_WARNING: Warning message generated by the user.
E_USER_NOTICE: Attention message caused by user.
E_STRICT: Encoding standardization warning, error that occurs at runtime.
E_RECOVERABLE_ERROR: A near-fatal runtime error. If not caught, it will be treated as E_ERROR.
E_ALL: Catch all errors and warnings.
The method to shield PHP error prompts is as follows
Method 1: Add @ before the function that may cause errors, and then or die("")
For example:
@mysql_connect(...) or die("Database Connect Error")
Method 2: Edit php.ini, search for "display_errors=", and change the value after "=" to "off.
Method 3: Add error_reporting(0) in front of the php script to block all errors. Tip.
Among them, error_reporting configures the level of error information reporting.
Syntax: int error_reporting(int [level]);
Return value: integer
Function type: PHP system function

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。


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