Question

numOfYears = 0
cpi = eval(input("Enter the CPI for July 2015: "))
if cpi.isdigit():
    while cpi < (cpi * 2):
        cpi *= 1.025
        numOfYears += 1
    print("Consumer prices will double in " + str(numOfYears) + " years.")
while not cpi.isdigit():
    print("Bad input")
    cpi = input("Enter the CPI for July 2015: ")

我收到以下错误。

AttributeError：＆＃39; int＆＃39;对象没有属性＆＃39; isdigit＆＃39;

由于我是编程新手，所以我真的不知道它要告诉我什么。我使用if cpi.isdigit():检查用户输入的内容是否为有效数字。

Answer 1

记录here CREATE TABLE dbo.PCT ( PCT_ID INT NOT NULL CONSTRAINT PK_PCT PRIMARY KEY CLUSTERED IDENTITY(1,1) , SomeChar VARCHAR(50) NOT NULL , SomeCharToInt AS CONVERT(INT, REPLACE(SomeChar, 'M', '')) ); CREATE INDEX IX_PCT_SomeCharToInt ON dbo.PCT(SomeCharToInt); INSERT INTO dbo.PCT(SomeChar) VALUES ('2015M08'); SELECT SomeCharToInt FROM dbo.PCT;是一种字符串方法。你不能为整数调用这个方法。

这一行，

isdigit()

cpi = eval(input("Enter the CPI for July 2015: "))用户输入整数。

evaluates

但如果删除>>> x = eval(input("something: ")) something: 34 >>> type(x) <class 'int'> >>> x.isdigit() Traceback (most recent call last): File "<stdin>", line 1, in <module> AttributeError: 'int' object has no attribute 'isdigit'方法（最好这样做），

eval

一切都会好的。

顺便使用没有sanitizin用户输入的eval可能会导致问题

考虑一下。

>>> x = input("something: ")
something: 54
>>> type(x)
<class 'str'>
>>> x.isdigit()
True

Answer 2

使用此：

if(str(yourvariable).isdigit()) :
    print "number"

isdigit()仅适用于字符串。

Answer 3

numOfYears = 0
# since it's just suppposed to be a number, don't use eval!
# It's a security risk
# Simply cast it to a string
cpi = str(input("Enter the CPI for July 2015: "))

# keep going until you know it's a digit
while not cpi.isdigit():
    print("Bad input")
    cpi = input("Enter the CPI for July 2015: ")

# now that you know it's a digit, make it a float
cpi = float(cpi)
while cpi < (cpi * 2):
    cpi *= 1.025
    numOfYears += 1
# it's also easier to format the string
print("Consumer prices will double in {} years.".format(numOfYears))

Answer 4

eval() is very dangerous! int()内置函数可以将字符串转换为数字。

如果您想在用户未输入数字时捕获错误，请使用try...except，如下所示：

numOfYears = 0

while numOfYears == 0:
    try:
        cpi = int(input("Enter the CPI for July 2015: "))
    except ValueError:
        print("Bad input")
    else:
        while cpi < (cpi * 2):
            cpi *= 1.025
            numOfYears += 1

print("Consumer prices will double in", numOfYears, "years.")

AttributeError：＆＃39; int＆＃39;对象没有属性＆＃39; isdigit＆＃39;

4 个答案: