小于运算符在 PHP 中无法正常工作，而循环

Question

我正在尝试根据每个积分的金额进行一些计算，以获得所请求金额中使用的总积分。请参考以下代码：<?php$amount_perpoints = bcdiv(622.9106666666667,1,2); // AMOUNT OF MONEY PER POINTS$request_amount = 3114.55; //REQUESTED AMOUNT OF POINTS$points = 0; // THIS WILL CONTAIN THE TOTAL POINTS$total_amount = 0; // THIS WILL INCREMENT ACCORDING TO THE PRODUCT OF THE CURRENT POINT AND AMOUNT PER POINTSwhile($total_amount < $request_amount){     $points = $points+0.50; //POINTS INCREMENTING BY 0.5    $total_amount = $points * $amount_perpoints;}echo $points;?>输出：5.50上面的场景输出，但我相信它应该只是.在迭代的点，并且 已经具有相同的值。为什么 while 循环仍然满足比较变量的两个值不小于但等于？5.505.005.00$total_amount$request_amount3114.55

Answer 1

您正在比较浮点数。尝试使用

while (bccomp($total_amount, $request_amount) === -1) {

Answer 2

使用小数分数作为浮点数进行计算时会发生错误。浮点数不能精确表示某些十进制数。仅使用 BC 数学函数进行此类计算。您也不需要循环。

$amount_perpoints = "622.91"; // AMOUNT OF MONEY PER POINTS

$request_amount = "3114.55"; //REQUESTED AMOUNT OF POINTS for result 5.0

//$request_amount = "3426.005"; //REQUESTED AMOUNT OF POINTS for result 5.5

$point_step = "0.50";

//calculation

$points = bcdiv($request_amount,$point_step,2);

$points = bcdiv($points,$amount_perpoints,0);

$points = bcmul($points,$point_step,1);

//output

var_dump($points);  //string(3) "5.0"

Answer 3

<?php

$amount_perpoints = bcdiv(622.9106666666667,1,2); // AMOUNT OF MONEY PER POINTS

$request_amount = 3114.55; //REQUESTED AMOUNT OF POINTS

$points = 0; // THIS WILL CONTAIN THE TOTAL POINTS

$new_points=0;

$total_amount = 0; // THIS WILL INCREMENT ACCORDING TO THE PRODUCT OF THE CURRENT POINT AND AMOUNT PER POINTS

while($total_amount < $request_amount){

    $points=$new_points;

    $new_points = $new_points+0.50; //POINTS INCREMENTING BY 0.5

    $total_amount = $new_points * $amount_perpoints;

}

echo $points;

?>

Answer 4

我认为@jeff是对的：

 $amount_perpoints = bcdiv(622.9106666666667,1,2); // AMOUNT OF MONEY PER POINTS

    $request_amount = 3114.55; //REQUESTED AMOUNT OF POINTS

    $points = 0; // THIS WILL CONTAIN THE TOTAL POINTS

    $total_amount = 0; // THIS WILL INCREMENT ACCORDING TO THE PRODUCT OF THE CURRENT POINT AND AMOUNT PER POINTS

    while($total_amount <= $request_amount){ 

        $points = $points+0.50; //POINTS INCREMENTING BY 0.5

        $total_amount = $points * $amount_perpoints;

    }

    echo $points;

由于你数到它达到期望的点，它的灵魂是少或等于。它给出的输出为 ： 5.5