我正在嘗試錯誤處理 doughnuts_gone 的輸入。用戶應(yīng)輸入列表的元素位置。例如，如果他們想以 18 美元的價格刪除 6 個奶油甜甜圈的訂單，那么您應(yīng)該輸入列表的位置；先列出so位置0，然后把2d列表中的列表元素位置去掉。我的程序的問題是，如果輸入的數(shù)字不在列表中可用元素的范圍內(nèi)，我不知道如何編寫 elif 語句：elif i != total_order[i]:簡化程序：def check_valid(prompt): while True: try: i = int(input(prompt)) if i == '': print("You must enter a value for the doughnut item you would like to change.") print() elif i != total_order[i]: print("Invalid") else: break except: break return itotal_order = [['Cream',6,18], ['Cookies',5,20], ['Jam',6,16]]for i in range(len(total_order)): print("{} {} {} Doughnuts = ${:.2f}".format(i, total_order[i][1],total_order[i][0],total_order[i][2]))doughnuts_gone = check_valid("Enter the number associated with the doughnut order you would like to remove? ")謝謝你！我希望這是有道理的！:)
1 回答
幕布斯7119047
TA貢獻(xiàn)1794條經(jīng)驗 獲得超8個贊
您將i變量檢查為字符串 ( if i == '':)，但它在前一行 ( i = int(input(prompt))) 中被強(qiáng)制轉(zhuǎn)換為整數(shù)。您應(yīng)該檢查列表的長度而不是這一行：elif i != total_order[i]:。由于這個問題，您的腳本無法正常工作。我寫了一個工作代碼，我已經(jīng)測試了它。請參閱下面我的代碼/測試。
此外，您的貨車會改進(jìn)您的代碼（例如：檢查輸入是否可以轉(zhuǎn)換為整數(shù)。）。
代碼：
def check_valid(prompt):
while True:
try:
i = input(prompt)
if not i:
print("You must enter a value for the doughnut item you would like to change.")
print()
elif int(i) > len(total_order)-1:
print("Invalid")
else:
break
except:
break
return int(i)
total_order = [['Cream', 6, 18], ['Cookies', 5, 20], ['Jam', 6, 16]]
for i in range(len(total_order)):
print("{} {} {} Doughnuts = ${:.2f}".format(i, total_order[i][1], total_order[i][0],
total_order[i][2]))
doughnuts_gone = check_valid(
"Enter the number associated with the doughnut order you would like to remove? ")
print("Valid value! Selected one: {}".format(total_order[doughnuts_gone]))
輸出：
>>> python3 test.py
0 6 Cream Doughnuts = $18.00
1 5 Cookies Doughnuts = $20.00
2 6 Jam Doughnuts = $16.00
Enter the number associated with the doughnut order you would like to remove? 3
Invalid
Enter the number associated with the doughnut order you would like to remove?
You must enter a value for the doughnut item you would like to change.
Enter the number associated with the doughnut order you would like to remove? 0
Valid value! Selected one: ['Cream', 6, 18]
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