如何计算总小时减去花费时间php

您可以尝试任何一种方法。方法NR.1是非常直接的，尽管有点冗长：

进近NR.1

<?php
    $totalHours = 16;
    $timeSpend  = "13:22:00";
    $baseDate   = "2016-05-11";
    $result     = null;
    $dateDiff   = null;
    // CONVERT BOTH $totalHours AND $timeSpend TO DATETIME OBJECTS USING AN ARBITRARY DATE AS BASE:::
    // HERE WE USED THE DATE: 2016-05-11 BUT YOU CAN USE ANY DATE.
    $date1      = new DateTime($baseDate);
    $date2      = new DateTime($baseDate . " " . $timeSpend );
    //ADD 30 HOUR TO $date1
    $date1->add(new DateInterval('PT' . $totalHours . "H"));
    //FIND THE DIFFERENCE BETWEEN THE 2.
    $dateDiff   = date_diff($date2, $date1);
    // IF $date1 IS GREATER THAN $date2; SIMPLY ASSIGN THE DATE DIFFERENCE TO $dateDiff
    // ELSE ASSIGN NULL TO $dateDiff
    if( ($date1 > $date2) ){
        $dateDiff   = date_diff($date2, $date1);
        //NOW FINALLY GET THE HOURS, MINUTES & SECONDS FROM THE RESULT
        $hour       = ($dateDiff->h < 10)? "0".$dateDiff->h : $dateDiff->h;
        $min        = ($dateDiff->i < 10)? "0".$dateDiff->i : $dateDiff->i;
        $sec        = ($dateDiff->s < 10)? "0".$dateDiff->s : $dateDiff->s;
        $result     = $hour . ":" . $min . ":" . $sec;
    }else{
        $dateDiff   = null;
    }
    //TEST YOUR RESULT...
    var_dump($result);      //DUMPS '16:38:00' TO THE OUTPUT STREAM...

进近NR.2

    <?php
        $totalHours = 30;
        $timeSpend  = "13:22:00";
        // CONVERT BOTH $totalHours & $timeSpend TO UNIX TIMESTAMP.
        $time1      = $totalHours * 60* 60;
        $time2      = strtotime($timeSpend);
        // CHECK IF $totalHours IS GREATER THAN $timeSpent
        // IF IT IS; SUBTRACT $timeSpent FROM $totalHours
        // AND ASSIGN THE DIFFERENCE TO $diff
        // OTHERWISE ASSIGN NULL TO $diff 
        $diff       = ($time1 > $time2) ? ($time1 - $time2) :null;
        // NOW REFORMAT DIFF USING PHP'S date FORMATTING FUNCTION:
        $diffTime   = date("H:i:s", $diff); 
        // JUST DO SOME TESTS TO SEE YOUR RESULT DUMPED TO THE OUTPUT STREAM:
        var_dump($diffTime);

您应该将所有值转换为秒。所以你可以使用这个转换你的时间

$str_time = "2:50";
sscanf($str_time, "%d:%d:%d", $hours, $minutes, $seconds);
$timeSeconds = isset($seconds) ? $hours * 3600 + $minutes * 60 + $seconds : $hours * 60 + $minutes;

然后你可以通过乘以3600 将小时转换为秒

$totalSeconds = $totalHours * 3600;

然后，您可以将其中一个从另一个中减去，以获得剩余的秒数。

$remainingSeconds = $totalSeconds - $timeSeconds;

然后将其格式化回时间

$timeText = gmdate("H:i:s", remainingSeconds );

您可以从总小时数中减去时间开销实例

$remaining = $totalhours - $timespend;
echo $remaining;