如果列超过特定数量，则PHP数组中断

如何解决如果列超过特定数量，则PHP数组中断

你好，我试图修改我2018年聘用的开发人员遗留下来的代码，但不是编码员，这确实给我造成了损失。我要在这里做的是，如果第一个表循环中有3个以上的城市，请使用此代码创建另一个表，然后重复此过程以创建表，而不是在现有表中添加新列，默认情况下，表的行数等于天以月为单位，但从数据库中将列作为位置。这是代码。

if (!empty($locations)) {
    echo "<table class='table table-striped tbl tbl-result text-center top1'>\r\n\t<thead>\r\n\t\t<tr>\r\n\t\t\t<th>";
    echo lang("label_date");
    echo "</th>\r\n\t\t\t";
    foreach ($locations as $location) {
        echo "\t\t\t<th>";
        echo $location->name;
        echo "</th>\r\n\t\t\t";
    }
    echo "\t\t</tr>\r\n\t</thead>\r\n\t<tbody>\r\n\t";
    foreach ($dates as $date) {
        echo "\t\r\n\t<tr>\r\n\t\t<td>";
        echo $date;
        echo "</td>\r\n\t\t";
        foreach ($locations as $location) {
            echo "\t\t\t";
            $data = $this->sales_model->result_row($date,$location->id,$sales);
            echo "\t\t\t";
            if ($data) {
                echo "\t\t\t<td>";
                echo $this->sales_model->append_zero($data);
                echo "</td>\r\n\t\t\t";
            } else {
                echo "\t\t\t<td></td>\r\n\t\t\t";
            }
            echo "\t\t";
        }
        echo "\t</tr>\r\n\t";
    }
    echo "\t</tbody>\r\n</table>\r\n";
}

我尝试了if else语句并继续中断，但无济于事，我什至不知道我现在在做什么。它显示在下面，我希望它在每个循环image

中打破3个城市

解决方法

您的问题有点含糊。但是，如果我对您的理解正确，则希望将每个日期的每个城市的销售数量限制为前三列（city1，city2，city3）。同时保持所有城市标题不变。

foreach可能不是执行此操作的最佳方法，但是鉴于您的深度，我将建议一些与您已经拥有的内容接近的东西。

尝试将foreach ($locations as $location) {的第二次出现替换为：

foreach ($locations as $locationIndex => $location) {
    if ($locationIndex > 2)
        break;

这假设$locations是具有顺序数字索引的简单数组。如果这不是您要执行的操作，请详细说明，以便我提供更准确的答案。

更新

有关一种可能方法的实时演示，请参见this eval。我使用heredoc语法来构建HTML，因为对于本示例而言，它更易于阅读。这是代码。您可以设置$numColumns来控制表的列数。

<?php

// Mock function to generate some random sales data,sometimes returning nothing.
function getLocationSalesForDate(DateTime $date,string $location)
{
    // Your business logic goes here.
    // Get the date as a string using DateTime::format().
    
    // Return a random mock value for this demo. Will randomly return NULL so as to simulate
    // your table view.
    return (mt_rand(0,3) === 1)?NULL:mt_rand(15,70);
}

$locations = ['city 1','city 2','city 3','city 4','city 5','city 6'];
$numColumns = 3;

$dateStart = new DateTime;
// 'P7D' means a period ('P') of 7 ('7') days ('D') from $dateStart. Consult the documentation of DateInterval's constructor for details.
$dateEnd = (clone $dateStart)->add(new DateInterval('P7D'));

// Segment your locations to however many you want to show on a single line.
foreach (array_chunk($locations,$numColumns) as $columnHeadings)
{
    // Output table heading for this group of locations.
    $html = <<<EOT
<table>
    <thead>
        <tr>
            <th>Date</th>

EOT;

    // Write out each location as a column heading.
    foreach ($columnHeadings as $columnHeading)
        $html .= <<<EOT
            <th>$columnHeading</th>

EOT;

    $html .= <<<EOT
        </tr>
    </thead>

EOT;

    // Output sales per day for this location.
    $html .= <<<EOT
    <tbody>

EOT;

    // Loop through each day between $dateStart and $dateEnd.
    $dateIterator = clone $dateStart;
    while ($dateIterator != $dateEnd)
    {
        // Start new row,print date on first column.
        $html .= <<<EOT
        <tr>
            <td>{$dateIterator->format('Y-m-d')}</td>

EOT;

        // Loop through this segment's locations and fetch sales for this day.
        foreach ($columnHeadings as $location)
        {
            // Retrieve mock sales data for this day on this location.
            $sales = getLocationSalesForDate($dateIterator,$location);
            
            // Record sales if we have any.
            if ($sales)
                // Have sales.
                $html .= <<<EOT
            <td>$sales</td>

EOT;
                else
                    // No sales for this day.
                    $html .= <<<EOT
            <td><!-- Empty cell if no sales recorded for this location on this day. --></td>

EOT;
        }
        
        // Close sales data row.
        $html .= <<<EOT
        </tr>

EOT;

        // Advance to next day for this location.
        $dateIterator->add(new DateInterval('P1D'));
    }
    
    // Close table for this location group.
    $html .= <<<EOT
    </tbody>
</table>

EOT;

    // Output table to user.
    echo $html;
}