round
round - 对浮点数进行四舍五入。round 函数语法如下:
round(float,precision)
其中参数 precision 表示小数点后面要保持的精度位数。如果不写参数 precision,表示四舍五入到整数位,比如:
echo round(3.4); // 3echo round(3.5); // 4echo round(3.6); // 4
如果 precision 为2,表示四舍五入到小数点后2位。示例如下:
echo round(1.95583, 2); // 1.96
如果参数 precision 为负数,表示四舍五入到小数点前。比如:
echo round(1241757, -3); // 1242000
floor
floor - 舍去法求整。floor 函数语法如下:
floor (value)
floor 函数返回不大于 value 的最大整数,即将 value 的小数部分舍去取整。示例如下:
echo floor(4); //4
echo floor(4.3); // 4echo floor(9.999); // 9
ceil
ceil - 进一法取整。ceil 函数语法如下:
ceil (value)
ceil 函数返回不小于 value 的最小整数。示例如下:
echo ceil(4); //4
echo ceil(4.3); // 5echo ceil(9.999); // 10
pow
pow - 求幂。pow 函数的语法如下:
pow (base,exp)
pow 函数返回 base 的 exp 次方的幂。下面的示例表示求 2 的8 次方,返回结果是256。
echo pow(2, 8); // 256
rand
rand - 产生一个随机整数。rand 函数语法如下:
rand (min,max)
rand 函数返回一个介于最小值 min 和最大值 max 之间 (包括min, max) 的随机整数。比如下面示例返回一个 2 到 6 之间的随机整数。
echo rand(2,6);
max
max - 返回参数中数值最大的值。
如果 max 函数只有一个参数且为数组,max 返回该数组中最大的值。
max 函数示例如下:
echo max(1, 3, 5, 6, 7); // 7echo max(array(2, 4, 5)); // 5
min
min - 返回参数中的最小值。
如果 min 函数只有一个参数且为数组,min 返回该数组中最小的值。
min 函数示例如下:
echo min(1, 3, 5, 6, 7); // 1echo min(array(2, 4, 5)); // 2
decbin
decbin - 十进制转换为二进制。decbin 函数语法如下:
decbin (number)
decbin 返回一个字符串,即返回参数 number 的二进制表示。示例如下:
echo decbin(12);
DE>decbin(12)DE> 返回的结果是:
1100
bindec
bindec - 二进制转换成十进制。bindec 函数语法如下:
bindec (binary_string)
bindec 函数将二进制字符串 binary_string 转换成一个十进制整数。示例如下:
echo bindec('110011'); //51
dechex, hexdec
dechex - 十进制转换为十六进制。
hexdec - 十六进制转换为十进制。
dechex, hexdec 函数示例如下:
echo dechex(47); //2f
echo hexdec('2f'); //47
decoct, octdec
decoct - 十进制转换为八进制
octdec - 八进制转换为十进制
decoct,octdec 函数示例如下:
echo decoct(12); //14
echo octdec('14'); //12

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PHPsessionstrackuserdataacrossmultiplepagerequestsusingauniqueIDstoredinacookie.Here'showtomanagethemeffectively:1)Startasessionwithsession_start()andstoredatain$_SESSION.2)RegeneratethesessionIDafterloginwithsession_regenerate_id(true)topreventsessi

In PHP, iterating through session data can be achieved through the following steps: 1. Start the session using session_start(). 2. Iterate through foreach loop through all key-value pairs in the $_SESSION array. 3. When processing complex data structures, use is_array() or is_object() functions and use print_r() to output detailed information. 4. When optimizing traversal, paging can be used to avoid processing large amounts of data at one time. This will help you manage and use PHP session data more efficiently in your actual project.

The session realizes user authentication through the server-side state management mechanism. 1) Session creation and generation of unique IDs, 2) IDs are passed through cookies, 3) Server stores and accesses session data through IDs, 4) User authentication and status management are realized, improving application security and user experience.


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