如何在php中进行变量类型转换？

Question

PHP, as most of us know, has weak typing. But what about those who don't require this. My problem is, here I have this code:

$total_price=0;
while(some condition)
{
    //1st iteration
    $total=0;
    $total = number_format(2450.0000*1,4);
    echo $total;//output-like 2,450.0000
    $total_price +=number_format($total,4);
    //2nd iteration
    $total=0;
    $total = number_format(1600.0000*2,4);
    echo $total;//output-like 3,200.0000
    $total_price +=number_format($total,4);
}

then echo $total_price; is 5 ....how? apart from number_format() here I want addition and multiplication of xxxx.0000,xxxx.0001 strictly have 4 decimal places e.g. 0.0000 + 0.0000 = 0.0000 not 0

Answer 1

A number is a number. A formatted number is a string. Numbers are for calculating and strings are for displaying. As soon as you try to do a calculation on a string, PHP will try to convert it back to a number again.

You should do the calculation first and only format it when you output it.