字符串切片是否？

Question

這個學期在Python上開設了一個課程，目前的作業遇到了麻煩。 直到現在為止，通過課堂上完成的示例和練習，仍然找不到任何東西。

Q1）固定

aN = raw_input("Enter a number with decimals")
bN = raw_input("Enter a binary number, 2 to 4 digits in length")

if (bN[-1] == 1):
    print "The binary number was odd so your number will contain 2 decimals"
    print "The number is now",aN[0:4],

elif (bN[-1] == 0):
    print "The binary number was even so your number will contain 1 decimal"
    print "The number is now",bN[0:3]

我希望它能夠打印出兩個語句，每個結果一個。 如果輸入的二進制數字以“ 1”結尾，它將以2個小數點吐出aN；如果輸入的二進制數字以“ 0”結尾，則將以1個小數點吐出aN。

它運行時，在顯示用戶為bN輸入的值后，它什么也不做

Q2）是否有更好的方法來查找小數點后的數字？ 切片僅在數字<10時有效。

編輯）對那個指出字符串的人，我完全忘記了:(

aN = raw_input("Enter a number with decimals")
bN = raw_input("Enter a binary number, 2 to 4 digits in length")

if (float(bN[-1]) == 1):
    print "The binary number was odd so your number will contain 2 decimals"
    print "The number is now",aN[0:4],

elif (float(bN[-1]) == 0):
    print "The binary number was even so your number will contain 1 decimal"
    print "The number is now",aN[0:3]

如果有人可以回答第二個問題，那就太好了。

Answer 1

raw_input()將輸入作為字符串。 在您的if條件中，您正在編譯一個帶有整數的字符串。 讓你if這樣，

if float(bN[-1]) == 1:
    print "The binary number was odd so your number will contain 2 decimals"
    print "The number is now %.2f" % float(aN)

elif float(bN[-1]) == 0:
    print "The binary number was even so your number will contain 1 decimal"
    print "The number is now", bN[0:3]

如果要在小數點后打印兩位數，則可以采用這種方法。

Answer 2

首先， raw_input()將輸入作為str 。

因此，將aN[-1]與int任何比較都會導致False 。 即您的代碼將始終運行else塊。

此外，您需要首先找到小數點的索引，然后計算是顯示一個還是兩個位置（或者處理沒有小數點的情況）

aN = raw_input("Enter a number with decimals")
bN = raw_input("Enter a binary number, 2 to 4 digits in length")

if (bN[-1] == '1'):
    print "The binary number was odd so your number will contain 2 decimals"
    if aN.find('.') == -1:
        print "The number is now ",aN
    else:
        print "The number is now ", aN[:aN.find('.')+3]

elif (bN[-1] == '0'):
    print "The binary number was even so your number will contain 1 decimal"
    if aN.find('.') == -1:
        print "The number is now ",aN
    else:
        print "The number is now ", aN[:aN.find('.')+2]

Answer 3

假設aN總是至少有1個小數，這應該是可行的。 您可以使用find()找到“”。 小數點。

aN = raw_input("Enter a number with decimals")
bN = raw_input("Enter a binary number, 2 to 4 digits in length")

if (bN[-1] == "1"):
    print "The binary number was odd so your number will contain 2 decimals"
    print "The number is now", aN[:aN.find(".")+3]

elif (bN[-1] == "0"):
    print "The binary number was even so your number will contain 1 decimal"
    print "The number is now", aN[:aN.find(".")+2]

例：

>>> aN
'1.12345'
>>> bN
'11'
>>> if (bN[-1] == "1"):
...     print "The binary number was odd so your number will contain 2 decimals"
...     print "The number is now", aN[:aN.find(".")+3]
... elif (bN[-1] == "0"):
...     print "The binary number was even so your number will contain 1 decimal"
...     print "The number is now", aN[:aN.find(".")+2]
...
The binary number was odd so your number will contain 2 decimals
The number is now 1.12