如果Elif Else聲明 (If Elif Else Statements)

The if/elif/else structure is a common way to control the flow of a program, allowing you to execute specific blocks of code depending on the value of some data.

if / elif / else結(jié)構(gòu)是控制程序流程的常用方法，它使您可以根據(jù)某些數(shù)據(jù)的值執(zhí)行特定的代碼塊。

如果聲明 (if statement )

If the condition following the keyword if evaluates as true, the block of code will execute. Note that parentheses are not used before and after the condition check as in other languages.

如果關(guān)鍵字if之后的條件評(píng)估為true ，則代碼塊將執(zhí)行。 請(qǐng)注意，在條件檢查之前和之后不會(huì)像其他語(yǔ)言一樣使用括號(hào)。

if True:print('If block will execute!')x = 5if x > 4:print("The condition was true!") #this statement executes

其他陳述 (else statement)

You can optionally add an else response that will execute if the condition is false:

您可以選擇添加一個(gè)else響應(yīng)，如果條件為false該響應(yīng)將執(zhí)行：

if not True:print('If statement will execute!') else:print('Else statement will execute!')

Or you can also see this example:

或者您也可以看到以下示例：

y = 3if y > 4:print("I won't print!") #this statement does not execute else:print("The condition wasn't true!") #this statement executes

Note that there is no condition following the else keyword - it catches all situations where the condition was false

請(qǐng)注意， else關(guān)鍵字后沒(méi)有條件-它捕獲條件為false所有情況

elif聲明 (elif statement)

Multiple conditions can be checked by including one or more elif checks after your initial if statement. Just keep in mind that only one condition will execute:

可以通過(guò)在初始if語(yǔ)句之后包含一個(gè)或多個(gè)elif檢查來(lái)檢查多個(gè)條件。 請(qǐng)記住，只有一種情況會(huì)執(zhí)行：

z = 7if z > 8:print("I won't print!") #this statement does not execute elif z > 5:print("I will!") #this statement will execute elif z > 6:print("I also won't print!") #this statement does not execute else:print("Neither will I!") #this statement does not execute

Note: only the first condition that evaluates as true will execute. Even though z > 6 is true, the if/elif/else block terminates after the first true condition. This means that an else will only execute if none of the conditions were true.

注意：只有第一個(gè)條件為true條件才會(huì)執(zhí)行。 即使z > 6為true ， if/elif/else塊if/elif/else在第一個(gè)true條件之后終止。 這意味著else僅在沒(méi)有條件true的情況下才會(huì)執(zhí)行。

嵌套if語(yǔ)句 (Nested if statements)

We can also create nested if’s for decision making. Before preceding please refer to the href=’https://guide.freecodecamp.org/python/code-blocks-and-indentation’ target=’_blank’ rel=‘nofollow’>indentation guide once before preceding.

我們還可以創(chuàng)建嵌套的if決策。 在開(kāi)始之前，請(qǐng)先參考href =“ https://guide.freecodecamp.org/python/code-blocks-and-indentation'target ='_ blank'rel ='nofollow'>縮進(jìn)指南。

Let’s take an example of finding a number which is even and also greater than 10

讓我們以發(fā)現(xiàn)一個(gè)等于甚至大于10的數(shù)字為例

python x = 34 if x % 2 == 0: # this is how you create a comment and now, checking for even.if x > 10:print("This number is even and is greater than 10")else:print("This number is even, but not greater 10") else:print ("The number is not even. So point checking further.")

This was just a simple example for nested if’s. Please feel free to explore more online.

這只是嵌套if的一個(gè)簡(jiǎn)單示例。 請(qǐng)隨時(shí)在線探索更多。

While the examples above are simple, you can create complex conditions using boolean comparisons and boolean operators.

盡管上面的示例很簡(jiǎn)單，但是您可以使用布爾比較和布爾運(yùn)算符創(chuàng)建復(fù)雜的條件。

內(nèi)聯(lián)python if-else語(yǔ)句 (Inline python if-else statement)

We can also use if-else statements inline python functions. The following example should check if the number is greater or equal than 50, if yes return True:

我們還可以使用if-else語(yǔ)句內(nèi)聯(lián)python函數(shù)。 以下示例應(yīng)檢查該數(shù)字是否大于或等于50，如果是，則返回True：

python x = 89 is_greater = True if x >= 50 else Falseprint(is_greater)

Output

輸出量

> True >

有關(guān)if / elif / else語(yǔ)句的更多信息： (More info on if/elif/else statements:)

• How to get out of if/else hell

  如何擺脫if / else地獄

• If/else in JavaScript

  JavaScript中的if / else

翻譯自: https://www.freecodecamp.org/news/if-elif-else-statements/

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