語法錯誤：名稱「變量」用來全局聲明之前

Question

我寫這個劇本在這裏：

http://www.codeskulptor.org/#user40_OuVcoJ2Dj1_8.py

我的錯在於驗證碼：

if 'i' not in globals(): 
    global i 
    if 'j' in globals(): 
     i = j 
    else: 
     i = 0 

我要分配i到如果j存在於全局範圍內，則爲j。如果j不存在，則i從0開始，如果輸入正確，則j可能會在腳本的後面進行全局聲明。

通過按左上角的播放來運行腳本。

Answer 1

這不是全局變量在Python中的工作方式。如果我猜中你的意圖，你想這個代碼：

if 'i' not in globals(): 
    global i 

來解釋類似「如果當前有沒有命名i一個全局變量，然後創建一個使用該名稱的全局變量。」這不是代碼所說的（正如所寫的，它沒有任何意義）。該代碼的最接近的翻譯是這樣的：

如果沒有名爲i全局變量，當我嘗試在此範圍內使用可變i，我指的是全球i（不存在），而不是創建僅存在於當前範圍內的新變量i。

global從來沒有創建什麼，它只告訴解釋器在哪裏尋找你指的是什麼。

一些可能有用的鏈接：

https://docs.python.org/2/faq/programming.html#what-are-the-rules-for-local-and-global-variables-in-python

https://infohost.nmt.edu/tcc/help/pubs/python/web/global-statement.html

Answer 2

能夠不將它們設置爲全局聲明，他們不會在globals()來電顯示。例如在你的程序的咆哮中，你可以聲明所有的全局變量，但是不要設置它們直到你想要的。

global test 
if 'test' in globals(): 
    print("test is in globals") 
else: 
    print ("test is not in globals") 

這將導致test is not in globals 但是如果你再這樣做，以後的值設置爲test它會在globals()

global test 
if 'test' in globals(): 
    print("test is in globals") 
    print(test) 
else: 
    print ("test is not in globals") 
    test=45 
if 'test' in globals(): 
    print("test is now in globals") 
    print(test) 
else: 
    print ("test is still not in globals") 

這將返回：

test is not in globals

test is now in globals

45

含義您可以聲明變量檢查的名稱以查看它是否在globals()中，然後設置它並檢查aga在。在你的代碼，你可以嘗試：

global i 
global j 
if 'i' not in globals(): 
    if 'j' in globals(): 
     i = j 
    else: 
     i = 0 
if 'j' not in globals(): 
    j = something 
else: 
    j =somethingElse 

Answer 3

這是一個失敗的腳本：

高清play_game（個體經營，猜測= 0）：

if guess == 0: #This part is ment for playing without typing the value into the function. This is ment for interactive gameplaying 
     x = True #While x == True the game will continue to spinn 
     while x == True: 
      if 'i' not in globals(): 
       global i 
       if 'j' in globals(): 
        i = j 
       else: 
        i = 0 
      else: 
       i += 1 
      rem = remaining_tries - i-1 
      if i >= remaining_tries: 
       x = False # x become false when i grows to or beyond remaining_tries which is a global variable. 
       print ' You did not guess the right number' 
       print 'The secret number was: ' + str(secret_number) #If yo dont guess the right value its nice to see what it was 
      else: 
       cin = input('Guess the number') 
       if int(cin) == secret_number: 
        print 'Congratulatins!! You guessed the right number!' 
        print 'If you dont remember the secret number was:' + str(secret_number) 
        x = False 
       elif int(cin) > secret_number: 
        print 'Lower' 
        print 'remaining tries = ' +str(rem) 
       elif int(cin) < secret_number: 
        print 'Higher' 
        print 'remaining tries = ' +str(rem) 
       else: 
        print 'You must enter a real number' 
    else: 
     if 'j' not in globals(): 
      global j 
      j = 0 
     else: 
      j += 1 

     rem = remaining_tries - j 
     if int(guess) == secret_number: 
      print 'Congratulatins!! You guessed the right number!' 
      print 'If you dont remember the secret number was:' + str(secret_number) 
     elif int(guess) > secret_number: 
      print 'Lower' 
      print 'remaining tries = ' +str(rem) 
     elif int(guess) < secret_number: 
      print 'Higher' 
      print 'remaining tries = ' +str(rem) 
     else: 
      print 'You must enter a real number' 
def close(self): 
    global i 
    global j 
    del i 
    del j