PHP If Else語句

PHP if else語句用于測試條件。愛掏網(wǎng) - it200.com在PHP中，有多種方法可以使用if語句。愛掏網(wǎng) - it200.com

• if
• if-else
• if-else-if
• 嵌套if

PHP if語句允許根據(jù)條件執(zhí)行代碼。愛掏網(wǎng) - it200.com只有當(dāng)條件為真時才會執(zhí)行。愛掏網(wǎng) - it200.com

如果條件為真，則if語句中存在的代碼塊會被執(zhí)行。愛掏網(wǎng) - it200.com

語法

if(condition){
//code to be executed
}

流程圖

示例

<?php
num=12;
if(num<100){
echo "$num is less than 100";
}
?>

輸出：

12 is less than 100

PHP If-else語句

PHP if-else語句在條件為真或假時執(zhí)行。愛掏網(wǎng) - it200.com

if-else語句與if語句稍有不同。愛掏網(wǎng) - it200.com如果指定的條件為 true ，它將執(zhí)行一塊代碼；如果條件為 false ，則執(zhí)行另一塊代碼。愛掏網(wǎng) - it200.com

語法

if(condition){
//code to be executed if true
}else{
//code to be executed if false
}

流程圖

示例

<?php
num=12;
if(num%2==0){
echo "num is even number";
}else{
echo "num is odd number";
}
?>

輸出：

12 is even number

PHP If-else-if 語句

PHP的if-else-if是一種特殊的語句，用于組合多個if…else語句。愛掏網(wǎng) - it200.com因此，我們可以使用該語句來檢查多個條件。愛掏網(wǎng) - it200.com

語法

if (condition1){  
//code to be executed if condition1 is true  
} elseif (condition2){    
//code to be executed if condition2 is true  
} elseif (condition3){    
//code to be executed if condition3 is true  
....
}  else{  
//code to be executed if all given conditions are false  
}  

流程圖

示例

<?php
    marks=69;       if (marks<33){  
        echo "fail";  
    }  
    else if (marks>=34 &&marks<50) {  
        echo "D grade";  
    }  
    else if (marks>=50 &&marks<65) {  
       echo "C grade"; 
    }  
    else if (marks>=65 &&marks<80) {  
        echo "B grade"; 
    }  
    else if (marks>=80 &&marks<90) {  
        echo "A grade";  
    }
    else if (marks>=90 &&marks<100) {  
        echo "A+ grade"; 
    }
   else {  
        echo "Invalid input";  
    }  
?>

輸出：

B Grade

PHP 嵌套if語句

嵌套if語句是指if語句包含在另一個if語句中。愛掏網(wǎng) - it200.com內(nèi)部的if語句只在外部if語句的指定條件為 true 時執(zhí)行。愛掏網(wǎng) - it200.com

句法

if (condition) {  
//code to be executed if condition is true 
if (condition) {  
//code to be executed if condition is true  
}  
} 

流程圖

示例

<?php
               age = 23;nationality = "Indian";
    //applying conditions on nationality and age
    if (nationality == "Indian")
    {
        if (age >= 18) {
            echo "Eligible to give vote";
        }
        else {  
            echo "Not eligible to give vote";
        }
    }
?>

輸出：

Eligible to give vote

PHP 開關(guān)示例

<?php
              a = 34;b = 56; c = 45;
    if (a < b) {
        if (a < c) {
            echo "a is smaller than b andc";
        }
    }
?>

輸出：

34 is smaller than 56 and 45