1.使用php的系统函数 number_format
$num = 1234567890;
echo number_format($num);
//1,234,567,890
echo number_format($num,2);
//1,234,567,890.00
echo number_format($num,2,'-','');
//1,234,567,890-00
2.自定义方法,调用php其他函数解决,这个方法的核心在于字符串反转,因为我们不确定这个数字有几位,所以从后往前加千分位
$num = 1234567890;
function thousandsSplit($num){
//反转字符串 0987654321
$num = strrev($num);
//使用逗号分割字符串 098,765,432,1,
$num = chunk_split($num, 3, ',');
//再次反转字符串 ,1,234,567,890
$num = strrev($num);
//去除最左边的逗号 1,234,567,890
$num = ltrim($num, ',');
echo $num;
//输出 1,234,567,890
}