PHP几个数学计算的内部函数学习整理_php技巧
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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