This article mainly shares with you how to write efficient PHP, hoping to help everyone.
1. Static static
Static variables start with the creation of the class and end with the death of the class; non-static variables start with the creation of the class instance and end with the death of the class instance. Static methods can be called directly, while instance methods must be called through instances, and static methods are much faster. Static methods always call the same memory and cannot be automatically destroyed, but can be destroyed by instantiation.
2. Echo is more efficient than print
Because echo does not return a value, while print returns an integer. Note that when echoing a large string, performance will be seriously affected if no adjustments are made. Use mod_deflate to open apached for compression or open ob_start to put the content into the buffer first.
3. Set the maximum number of times before looping, not during the loop;
For example, it is calculated every time in the for loop.
4. Destroy variables to release memory, especially large arrays;
Arrays and objects are special in PHP Memory usage is due to the underlying zend engine of PHP. Generally speaking, the memory utilization of PHP arrays is only 1/10. In other words, an array with 100M of memory in C language will cost 1G in PHP. . Especially in systems where PHP is used as a backend server, the problem of excessive memory consumption often occurs.
5. requiere_once() consumes more resources;
This is because requiere_once requires Determine whether the file has been referenced, so try not to use it if possible. Commonly used require/include methods to avoid.
6. Use absolute paths in includes and requires.
#If a relative path is included, PHP will traverse the include_path to find the file. Using absolute paths will avoid such problems, so it will take less time to resolve the operating system path.
7. Can use PHP’s internal string manipulation functions In this case, try to use them instead of regular expressions; because its efficiency is higher than regular expressions;
str_replace character replacement is faster than regular replacement preg_replace, but strtr is 1/4 faster than str_replace ;
Also don’t do unnecessary substitutions. Even if there is no substitution, str_replace will allocate memory for its parameters. very slow! Solution: Use strpos to search first (very fast) to see if replacement is needed, and then replace if necessary. Efficiency: - If replacement is required: Efficiency is almost equal, the difference is around 0.1%. If no substitution is required: using strpos is 200% faster.
##8. It is best not to use @, using @ to cover up errors will reduce the running speed of the script;
Using @ actually has many operations in the background. The efficiency difference between using @ and not using @ is: 3 times. Especially do not use @ in a loop. In the test of 5 loops, even if you use error_reporting(0) to turn off the error first and then turn it on after the loop is completed, it is faster than using @.
9.$row['id'] is 7 times faster than $row[id]; It is recommended to develop the habit of adding quotes to array keys;
10.Don’t use functions in loops
##For example, For($x=0; $x
11. Creating an undeclared local variable is 9-10 times slower than an already defined local variable
12.Single quotes instead of double quotes to contain strings
13.Apache parses a PHP The script is 2 to 10 times slower than parsing a static HTML page.
Try to use more static HTML pages and less scripts. 14. Don’t just copy variables Sometimes in order to make the PHP code neater, some PHP newbies (including me) will copy the predefined variables into a variable with a shorter name. In fact, the result of this is doubling the memory consumption, which will only make the program slower. 15. Use the selective branch statement switch case is better than using multiple if, else if statements, and the code is easier to read and maintain. 16. Try to do as few file operations as possible, although PHP’s file operation efficiency is not low; You can use file_get_contents instead of file, fopen, feof, fgets 17. Use PHP internals as much as possible Function 18. foreach is more efficient, try to use foreach instead of while and for loop; ##19. Do not declare variables inside the loop, especially large variables: objects 20. For global variables, you should unset() them after use; 21. Using ++$i to increment $i++ will be slower than ++$i. This difference is specific to PHP and does not apply to other languages. Post-increment actually creates a temporary variable that is subsequently incremented. Prefix increment increases directly on the original value. This is a form of optimization, as done by Zend's PHP optimizer. Related recommendations: 6 Efficient PHP Frameworks for Creating Web Applications Learn the essence of PHP, write efficient PHP code for performance_PHP tutorial Learn the essence of PHP, write efficient PHP code for automatic testing_PHP tutorial
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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。

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。

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。

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。

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。


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