PHP Switch語句

PHP switch語句用于從多個(gè)條件中執(zhí)行一條語句。愛掏網(wǎng) - it200.com它的工作方式類似于PHP的if-else-if語句。愛掏網(wǎng) - it200.com

語法

switch(expression){    
case value1:    
 //code to be executed
 break;
case value2:    
 //code to be executed
 break;
......    
default:     
 code to be executed if all cases are not matched;  
}

關(guān)于switch case的重要注意事項(xiàng)

1. default 是可選語句。愛掏網(wǎng) - it200.com即使不重要，default必須始終是最后一個(gè)語句。愛掏網(wǎng) - it200.com
2. switch語句中只能有一個(gè) default 。愛掏網(wǎng) - it200.com多個(gè)default可能導(dǎo)致 致命錯(cuò)誤 。愛掏網(wǎng) - it200.com
3. 每個(gè)case可以有一個(gè) break 語句，用于終止語句序列。愛掏網(wǎng) - it200.com
4. 在switch中， break 語句是可選的。愛掏網(wǎng) - it200.com如果不使用break，所有與匹配case值相對(duì)應(yīng)的語句都會(huì)執(zhí)行。愛掏網(wǎng) - it200.com
5. PHP允許在switch表達(dá)式中使用數(shù)字、字符、字符串和函數(shù)。愛掏網(wǎng) - it200.com
6. 允許嵌套switch語句，但會(huì)使程序變得更復(fù)雜且不易閱讀。愛掏網(wǎng) - it200.com
7. 你可以使用分號(hào)(;)代替冒號(hào)(:)，不會(huì)產(chǎn)生任何錯(cuò)誤。愛掏網(wǎng) - it200.com

PHP Switch流程圖

PHP Switch 示例

<?php    
num=20;    
switch(num){    
case 10:    
echo("number is equals to 10");    
break;    
case 20:    
echo("number is equal to 20");    
break;    
case 30:    
echo("number is equal to 30");    
break;    
default:    
echo("number is not equal to 10, 20 or 30");    
}   
?>

輸出：

number is equal to 20

PHP字符的switch語句

檢查元音和輔音的程序

我們將傳遞一個(gè)字符給switch表達(dá)式來檢查它是元音還是輔音。愛掏網(wǎng) - it200.com如果傳遞的字符是A、E、I、O或U，它將是元音，否則是輔音。愛掏網(wǎng) - it200.com

<?php    
    ch = 'U';
    switch (ch)
    {   
        case 'a': 
            echo "Given character is vowel";
            break;
        case 'e': 
            echo "Given character is vowel";
            break;
        case 'i': 
            echo "Given character is vowel";
            break;
        case 'o': 
            echo "Given character is vowel";
            break;  
        case 'u': 
            echo "Given character is vowel";
            break;
        case 'A': 
            echo "Given character is vowel";
            break;
        case 'E': 
            echo "Given character is vowel";
            break;
        case 'I': 
            echo "Given character is vowel";
            break;
        case 'O': 
            echo "Given character is vowel";
            break;
        case 'U': 
            echo "Given character is vowel";
            break;
        default: 
            echo "Given character is consonant";
            break;
    }
?>  

輸出：

Given character is vowel

PHP中的字符串 switch 語句

PHP允許在switch表達(dá)式中傳遞字符串。愛掏網(wǎng) - it200.com讓我們通過在switch case語句中傳遞字符串來看下面的課程時(shí)長示例。愛掏網(wǎng) - it200.com

<?php    
    ch = "B.Tech";
    switch (ch)
    {   
        case "BCA": 
            echo "BCA is 3 years course";
            break;
        case "Bsc": 
            echo "Bsc is 3 years course";
            break;
        case "B.Tech": 
            echo "B.Tech is 4 years course";
            break;
        case "B.Arch": 
            echo "B.Arch is 5 years course";
            break;
        default: 
            echo "Wrong Choice";
            break;
    }
?>  

輸出：

B.Tech is 4 years course

PHP的switch語句是穿透的

PHP的switch語句是穿透的。愛掏網(wǎng) - it200.com這意味著在找到第一個(gè)匹配項(xiàng)后，如果沒有找到break語句，它將執(zhí)行所有的語句。愛掏網(wǎng) - it200.com

<?php    
    ch = 'c';
    switch (ch)
    {   
        case 'a': 
            echo "Choice a";
            break;
        case 'b': 
            echo "Choice b";
            break;
        case 'c': 
            echo "Choice c";    
            echo "</br>";
        case 'd': 
            echo "Choice d";
            echo "</br>";
        default: 
            echo "case a, b, c, and d is not found";
    }
?>  

輸出：

Choice c
Choice d
case a, b, c, and d is not found

PHP嵌套的switch語句

嵌套的switch語句意味著在另一個(gè)switch語句內(nèi)部使用switch語句。愛掏網(wǎng) - it200.com有時(shí)會(huì)導(dǎo)致混淆。愛掏網(wǎng) - it200.com

<?php    
    car = "Hyundai";model = "Tucson";  
        switch( car )         {             case "Honda":                 switch(model )   
                {  
                    case "Amaze":  
                           echo "Honda Amaze price is 5.93 - 9.79 Lakh."; 
                        break;  
                    case "City":  
                           echo "Honda City price is 9.91 - 14.31 Lakh.";  
                        break;   
                }  
                break;  
            case "Renault":  
                switch( model )                  {                     case "Duster":                         echo "Renault Duster price is 9.15 - 14.83 L.";
                        break;                     case "Kwid":                            echo "Renault Kwid price is 3.15 - 5.44 L.";
                        break;                 }                 break;             case "Hyundai":                 switch(model )   
                {  
                    case "Creta":  
                        echo "Hyundai Creta price is 11.42 - 18.73 L.";
                        break;  
        case "Tucson":  
                           echo "Hyundai Tucson price is 22.39 - 32.07 L.";
                        break; 
                    case "Xcent":  
                           echo "Hyundai Xcent price is 6.5 - 10.05 L.";
                        break;  
                }  
                break;   
        }
?>  

輸出：

Hyundai Tucson price is 22.39 - 32.07 L.