


Operators and expressions are the most basic knowledge in learning PHP. This article explains some applications and techniques of operators and expressions in PHP through examples, as well as what needs to be paid attention to. Friends in need can refer to it. one time.
php Operators and expressions
1. Classification of operators
1. By operand Category
1.!true // Unary operator
2.$a+$b // Binary operator
3.true ? 1:0 // Ternary operator
2. Classification by operation function
(1) Arithmetic operators
1.+,-,x,/,%(remainder)
(2) String operator
1.. // For example: $a = 'abc'.'efg';
(3) Assignment operator
1.= // Simple assignment
2.+=, -=, X=, /=, %=, .= // Compound assignment
3.++($a++, ++$ a), --($a--,--$a) // Increment and decrement
4.&($a = 1;$b = &a) //Reference assignment
(4) Comparison operators
1.==, ===(constantly equal), !=, !===, (not equal), ,
(5) Logical operators
1.// The ones inside the brackets have higher priority than those outside the brackets
2.&&(and), ||(or), !(not), ), ^(bitwise XOR), >(right shift)
2. Arithmetic operators
% remainder, common usage: 1) Integer division operation 2) Controlling the value rangeExample: Determine whether it is a leap year (one leap year every four years, no leap year, no leap year, and another leap year after four hundred years)
// %会把两边的数转成整型后在整除 // %两边不能用小数或负数 if ((($year%4 == 0) && ($year%100 != 0)) || $year%400 == 0) echo "闰年"; else echo "平年";
3. Assignment operators
##//先自身加10,然后赋值给自己,等价于 $a=$a+10
$a += 10;
//前置递增递减,先递增递减再赋值
++$a
//先赋值,再递增递减
$a++
//实例
$a = 10;
$b = $a++
$c = --$b
结果:a=11 b=9 c=9
Tips: Pay attention to the difference with or, two or True = true Logical operator short circuit 1, && //If one is false, then no operation will be performed later, it must be false
2, || //If one is true, then no operation will be performed later, it must be false True
fopen ("test.php","r") or die("failure");
Tips: There is no short-circuit feature for operator & |
5. Bit operators
The above is the detailed content of Detailed explanation of php operators and expression usage examples. For more information, please follow other related articles on the PHP Chinese website!

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。

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。

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。

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。


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