Summary of how to use operators in php_PHP tutorial
Arithmetic operators
1. Arithmetic operators: +, -, *, /, %.
2. Increment/decrement operators: such as $a++,$a--,++$a,--$a.
For example:
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echo '$a='.$a."||".'$c='.$c.'
$c=++$a; //increment first, then assign value. $a=$a+1,$c=$a $d=--$b; //decrement first, then assign value. $b=$a-1, $d=$b
echo '$a='.$a."||".'$c='.$c.' '; //$b=4,$d=4
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Ternary operator
(expr1) ? (expr2) : (expr3); Explanation: If condition "expr1" is true, execute statement "expr2", otherwise execute "expr3".
The following statements are syntactically correct, they omit the second or third "element" in small dequotation marks:代码如下 | 复制代码 |
$a=10;$b=7; 改变一下 $a=10;$b=7; |
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$a>$b ? print "Yes" : ""; $a>$b ? '': print 'No'; |
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$str = $_GET['abc'] ? 'wangjinbo' : 'wjb'; |
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$a=10;$b=7; if($a++>8 || $b++>7){ //$a++>8 is true, $b++>7 will not be executed echo 'OK!'; } echo 'a='.$a.'b='.$b; // Output OK, a=11,b=7 Change it up $a=10;$b=7; if($a++>10 && $b++>7){ //$a++>8 is false, $b++>7 will not be executed echo 'OK!'; } echo 'a='.$a.'b='.$b; // a=11,b=7 |
Details: and && both represent logical AND, what is their difference?
Mainly reflected in priority
Priority of and
代码如下 | 复制代码 |
and
or
如: $a=false || true; //&& > = > and ;先比较false || true,再赋值 $b=false or true; //|| > = > or ;先赋值$b=false,再比较,所以结果是false var_dump($a,$b); //bool(true) bool(false) |
Bitwise operators
Displacement is a mathematical operation in PHP. Bits moved out in any direction are discarded. When shifting left, the right side is padded with zeros, and the sign bit is moved away, meaning that the sign is not preserved. When shifting right, the left side is padded with sign bits, which means the sign is preserved.
Use parentheses to ensure desired precedence. For example, $a & $b == true performs comparison first and then performs bitwise AND; while ($a & $b) == true performs bitwise AND first and then performs comparison.
Pay attention to data type conversion. If both left and right arguments are strings, the bitwise operators operate on the ASCII values of the characters.
PHP’s ini setting error_reporting uses bitwise values,
Real-life examples of turning off a bit are provided. To show except prompt level
For all errors except php.ini, use this:
E_ALL & ~E_NOTICE
The specific operation method is to first obtain the value of E_ALL:
00000000000000000111011111111111
Then get the value of E_NOTICE:
00000000000000000000000000001000
Then negate it via ~:
11111111111111111111111111110111
Finally, use bitwise AND (&) to get the bits that are set (to 1) in both values:
00000000000000000111011111110111
Another method is to use bitwise XOR (^) to get only the values in
The bits set in one of the values:
E_ALL ^ E_NOTICE
error_reporting can also be used to demonstrate how to set the bit. Show only errors and recoverables
The wrong way is:
E_ERROR | E_RECOVERABLE_ERROR
That is to say, E_ERROR
00000000000000000000000000000001
and E_RECOVERABLE_ERROR
00000000000000000001000000000000
Use the bitwise OR (|) operator to get the result of a bit being set in any value:
00000000000000000001000000000001
Example #1 AND, OR and XOR bitwise operators for integers
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Comparison operators
If comparing a number to a string or comparing strings involving numeric content, the string is converted to a numeric value and the comparison is performed as a numeric value. This rule also applies to switch statements. When comparing with === or !==, no type conversion is performed because both types and values are compared.
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var_dump("1" == "01"); // 1 == 1 -> true var_dump("10" == "1e1"); // 10 == 10 -> true var_dump(100 == "1e2"); // 100 == 100 -> true switch ("a") { case 0: echo "0"; Break; case "a": // never reached because "a" is already matched with 0 echo "a"; Break; } ?>
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For multiple types, comparison operators compare according to the following table (in order).

What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.


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