不需要explode任何东西：
$str_time = "23:12:95";
$str_time = preg_replace("/^([\d]{1,2})\:([\d]{2})$/", "00:$1:$2", $str_time);
sscanf($str_time, "%d:%d:%d", $hours, $minutes, $seconds);
$time_seconds = $hours * 3600 + $minutes * 60 + $seconds;
而且，如果您不想使用正则表达式：
$str_time = "2:50";
sscanf($str_time, "%d:%d:%d", $hours, $minutes, $seconds);
$time_seconds = isset($hours) ? $hours * 3600 + $minutes * 60 + $seconds : $minutes * 60 + $seconds;
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