The following are some commonly used PHP system constants:
__FILE__ current PHP file name
__LINE__ in the current PHP file Number of lines
__FUNCTION__ Currently executed function
__CLASS__ Currently executed class
PHP_VERSION PHP version
PHP_OS Current server operating system
TRUE Same as true
FALSE Same as false
E_ERROR Go to the nearest error location
E_WARNING Go to the nearest warning location
E_PARSE Syntax error There is an exception in
E_NOTICE in PHP language
M__PI Pi
M__E Scientific constant e
M__LOG2E Logarithm of e with base 2
M_LOG10E The logarithm of e with base 10
M_LN2 The natural logarithm of 2
M_LN10 The natural logarithm of 10
The content of PHP system constants is introduced Here, I hope it will be helpful to everyone.

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”。

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。

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。

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。

查找方法:1、用strpos(),语法“strpos("字符串值","查找子串")+1”;2、用stripos(),语法“strpos("字符串值","查找子串")+1”。因为字符串是从0开始计数的,因此两个函数获取的位置需要进行加1处理。

在PHP中,可以利用implode()函数的第一个参数来设置没有分隔符,该函数的第一个参数用于规定数组元素之间放置的内容,默认是空字符串,也可将第一个参数设置为空,语法为“implode(数组)”或者“implode("",数组)”。

转化方法:1、使用“mb_substr($url,stripos($url,"?")+1)”获取url的参数部分;2、使用“parse_str("参数部分",$arr)”将参数解析到变量中,并传入指定数组中,变量名转为键名,变量值转为键值。

在php中,可以利用ltrim()函数来去掉字符串首位的tab空白符,语法为“ltrim(string)”;当只给ltrim()函数传入一个参数,用于规定要检查的字符串时,可删除该字符串开始位置的空白字符(例空格、tab制表符、换行符等)。


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