我有一個(gè)非常愚蠢的問題。我正在從 mysql 中提取收入和支出的總額，然后我想從收入中減去支出。由于某種原因，結(jié)果不是剩下的，而是顯示了收入數(shù)字 - 支出數(shù)字。代碼如下function total_by_type_between_dates($type, $start, $end){ global $uc_con; $start = strtotime ($start); $end = strtotime ($end); $sql = "SELECT SUM(amount) AS total FROM account WHERE `time` > $start && `time` < $end && `type` = '$type'"; $result = $uc_con->query($sql); $row = $result->fetch_array(MYSQLI_ASSOC); $total = number_format((float)$row['total'], 2, '.', ''); echo $total;}function total_expense_between_dates($start, $end){ global $uc_con; $start = strtotime ($start); $end = strtotime ($end); $sql = "SELECT SUM(amount) AS total FROM account WHERE `time` > $start && `time` < $end && `type` != 'income' && `type` != 'mileage'"; $result = $uc_con->query($sql); $row = $result->fetch_array(MYSQLI_ASSOC); $total = number_format((float)$row['total'], 2, '.', ''); return $total;}echo total_by_type_between_dates('income', $date_begining, $date_ending)-total_expense_between_dates($date_begining, $date_ending);奇怪的是結(jié)果顯示如下：2770.69-407.42而不是2363.29誰能告訴我可能是什么原因造成的
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TA貢獻(xiàn)1804條經(jīng)驗(yàn) 獲得超3個(gè)贊
您的total_by_type_between_dates函數(shù)正在回顯其結(jié)果而不是返回它。所以你的
echo total_by_type_between_dates('income', $date_begining, $date_ending)-total_expense_between_dates($date_begining, $date_ending);有效地
echo total_by_type_between_dates('income', $date_begining, $date_ending);
echo null-total_expense_between_dates($date_begining, $date_ending);并且null在數(shù)字上下文中被視為 0，因此您看到的結(jié)果是：2770.69-407.42
改變
echo $total;
在total_by_type_between_dates到
return $total;
并且代碼將按預(yù)期工作。
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