Question

我可以在switch语句中放置条件语句吗？ ex - switch（$ totaltime＆lt; = 13）除了php之外，其他语言的兼容性如何？

$totaltime=15;

switch ($totaltime<=13) {

case ($totaltime <= 1):
echo "That was fast!";
break;

case ($totaltime <= 5):
echo "Not fast!";
break;

case ($totaltime >= 10 && $totaltime<=15):
echo "That's slooooow";
break;
}

修改

$totaltime=12; 
switch (false) { 
case ($totaltime <= 1): 
echo "That was fast!"; 
break; 
case ($totaltime <= 5): 
echo "Not fast!";
break;
case ($totaltime >= 10 && $totaltime<=13): 
echo "That's slooooow"; 
break; 
default: // do nothing break; 
}

在这种情况下绅士为什么alwyas显示输出为＆＃34;那很快！＆＃34;？

Answer 1

Switch仅检查第一个条件是否等于第二个条件，这样：

switch (CONDITION) {
    case CONDITION2:
        echo "CONDITION is equal to CONDITION2";
    break;
}

所以你必须这样做：

switch (true) {
    case $totaltime <= 1: #This checks if true (first condition) is equal to $totaltime <= 1 (second condition), so if $totaltime is <= 1 (true), is the same as checking true == true.
        echo "That was fast!";
    break;

    case $totaltime <= 5:
        echo "Not fast!";
    break;

    case $totaltime >= 10 && $totaltime<=13:
        echo "That's slooooow";
    break;
}

而不是这个我会去if-elseif语句。乍看之下更容易理解：

if ($totaltime <= 1) {
    echo "That was fast!";
} elseif($totaltime <= 5) {
    echo "Not fast!";
} elseif($totaltime >= 10 && $totaltime<=13) {
    echo "That's slooooow";
}

Answer 2

是的，你可以（除了交换机内的比较）

$totaltime=12;

switch (true) {

case ($totaltime <= 1):
echo "That was fast!";
break;

case ($totaltime <= 5):
echo "Not fast!";
break;

case ($totaltime >= 10 && $totaltime<=13):
echo "That's slooooow";
break;

default:
// do nothing
break;
}

Answer 3

是的，您可以从PHP的交换机文档中获取：

switch语句类似于同一表达式上的一系列IF语句。在许多情况下，您可能希望将相同的变量（或表达式）与许多不同的值进行比较

当案例具有常量值时，就像说，案例值==切换值，但你可以为案例设置更复杂的表达式。

PHP-使用条件开关切换case语句

3 个答案: