Echo 语句以某种方式修复了 while 循环问题，需要去掉 echo

Question

我正在尝试制作一个线图，显示每天的应计总数。我写了一个循环来查找每天的总数，我认为这个逻辑是有道理的。为了验证正在比较的日期，我添加了两个 echo 语句来进行直观比较并尝试逐步了解正在发生的情况。当我输入两个 echo 语句时，数组开始按我的预期工作，但我不知道为什么。我尝试 var-dump 来查看它是否是变量的类型，但在任何一种情况下它都会将 $date 称为字符串。但是，如果没有这两个日期数组位置上的 echo 语句，我得到的总数是我应有的总数的两倍，因为本月到目前为止只有 17 天，而我得到了 33 或 34 个条目。有没有办法对其进行格式化，以便它继续工作，但取出 echo 语句，因为这最终将是导入的 png 文件？我确信答案很简单，但我对此很陌生。我很感激任何答案。

while ($rows=odbc_fetch_row($result)){

    $unit=odbc_result($result,"unit_cost"); /*Rounding for Unit Cost*/
    $unit_cost=round($unit,2);

    $ext=odbc_result($result,"ext_cost"); /*Rounding for Extended Cost*/
    $ext_cost=round($ext,2);

    $date[]=odbc_result($result,"date_created");

    echo (prev($date));
    echo (end($date));

    if (prev($date) != end($date)){ //if previous element's date does not match current array's date:
        $total[]=$sum;    //report total summation to entry in total array, rezero sum variable.
        $sum = 0;
        $sum = $sum + $ext;
    }
    else{ //if both element's have same date:
        $sum=$sum + $ext; //add extended cost of this line to total $sum, to be reported as an element in $total once this date is finished.
    }

}//end while

print_r($total);

Answer 1

调用

prev()

和

end()

实际上会移动数组的内部记录指针，这在主动读写时会产生奇怪的行为。在

if()

内调用这些函数来进行

!=

比较会将数组的指针移动到一个令人困惑的地方。

替代

prev()/end()

的解决方案是将从 ODBC 获取的行单独存储在变量中，并在每次循环迭代期间将其存储为

$previous

以与当前迭代的数组进行比较。

此外，我建议将其切换为

odbc_fetch_row()，而不是 odbc_result()

 和 

odbc_fetch_array()，它将返回关联数组，从而消除对

odbc_result()

的调用。

// Initialize an empty var for the comparison date
$prev_date = null;
// Init $sum for later...
// It looks like you need this...
$sum = 0;

// Get $row as an assoc array
while ($row = odbc_fetch_array($result)) {

    $unit = $row['unit_cost']; /*Rounding for Unit Cost*/
    $unit_cost = round($unit, 2);

    $ext = $row['ext_cost']; /*Rounding for Extended Cost*/
    $ext_cost = round($ext, 2);

    // Store the new date in $current_date
    $current_date = $row['date_created'];
    // Store it onto $date
    $date[] = $current_date;

    // And you can safely echo these or not...
    echo "Current date: " . $current_date;
    echo "Previous date: " . $prev_date;

    // Now compare with the previous date value
    if ($prev_date != $current_date) { //if previous element's date does not match current array's date:

        // Where does $sum come from at first? Is it initialized outside the loop?
        $total[] = $sum;    //report total summation to entry in total array, rezero sum variable.
        $sum = 0;
        $sum = $sum + $ext;
    }
    else { //if both element's have same date:
        $sum = $sum + $ext; //add extended cost of this line to total $sum, to be reported as an element in $total once this date is finished.
    }

    // After the comparison, store the current into previous
    // for the next loop comparison
    $prev_date = $current_date;
}//end while

print_r($total);

Answer 2

将代码分解为逻辑单元。首先，拉取数据。其次，执行任何计算。

$extCosts = array();

while ( odbc_fetch_row($result) ) { // http://php.net/manual/en/function.odbc-result.php

    $ext = odbc_result($result,"ext_cost");
    $ext_cost = round($ext,2);
    $date = odbc_result($result,"date_created");

    $extCosts[$data][] = $ext_cost;

}

print_r($extCosts);

数组 $extCosts 应该类似于：

2015-01-01
    2
    1
    5
2015-01-02
    2
2015-01-03
    4
    7

然后简单地使用 PHP 的数组函数来获取总和

$sums = array();
foreach ( $extCosts as $k => $v ) {
    $sums[$k] = array_sum($v);
}

print_r($sums);