<?php
/**
* Created by PhpStorm.
* User: JIAN.HUANG
* Date: 2016/4/26
* Time: 8:52
*/
echo "number demo<br>";
$stringNumber = '3';
$number = 5;
echo $stringNumber * $number; //output: 15
echo "<br>";
//the $stringNumber is converted to 15
$stringNumber = '15a4';
$number = 5;
echo $stringNumber * $number; //output: 75
echo "<br>";
//the $stringNumber is converted to 0
$stringNumber = 'aaa';
$number = 5;
echo $stringNumber * $number; //output: 0
echo "<br>";
//The variables are converted to strings
$stringNumber = 3;
$number = 5;
echo $stringNumber . $number; //output: 35
echo "<br>";
$number = '15';
echo number_format($number, 2); //output: 15.00
echo "<br>";
$number = 1234.56;
echo number_format($number); //output: 1235
echo "<br>";
$number = 1234.56;
echo number_format($number, 2, ',', ' '); //output: 1 234,56
echo "<br>";
$number = 1234.5678;
echo number_format($number, 2, '.', ''); //output: 1234.57
echo "<br>";
$number = 1234.5618;
echo number_format($number, 2, '.', ''); //output: 1234.56
echo "<br>";
number_format
string number_format ( float $number [, int $decimals = 0 ] )
string number_format ( float $number , int $decimals = 0 , string $dec_point = "." , string $thousands_sep = "," )
本函数可以接受1个、2个或者4个参数（注意：不能是3个）:
如果只提供第一个参数，number的小数部分会被去掉 并且每个千位分隔符都是英文小写逗号”,”
如果提供两个参数，number将保留小数点后的位数到你设定的值，其余同楼上
如果提供了四个参数，number 将保留decimals个长度的小数部分, 小数点被替换为dec_point，千位分隔符替换为thousands_sep
