使用Python中的try/except将String转换为Int

Question

所以我很沮丧如何使用try/except函数将字符串转换为int.有谁知道如何做到这一点的简单功能？我觉得我对字符串和整体仍然有点朦胧.我非常有信心整数与数字有关.字符串......不是那么多.

Answer 1

重要的是具体说明在尝试使用try/except块时要尝试捕获的异常.

string = "abcd"
try:
    i = int(string)
    print i
except ValueError:
    #Handle the exception
    print 'Please enter an integer'

Try/Excepts功能强大,因为如果某些内容可能以多种不同的方式失败,您可以指定程序在每种失败案例中的反应方式.

Answer 2

这里是:

s = "123"
try:
  i = int(s)
except ValueError as verr:
  pass # do job to handle: s does not contain anything convertible to int
except Exception as ex:
  pass # do job to handle: Exception occurred while converting to int

Answer 3

首先,try/except不是函数,而是语句.

要在Python中将字符串(或任何其他可以转换的类型)转换为整数,只需调用int()内置函数即可.int()将raise一个ValueError如果失败的话,你应该明确抓住这个:

在Python 2. x中:

>>> for value in '12345', 67890, 3.14, 42L, 0b010101, 0xFE, 'Not convertible':
...     try:
...         print '%s as an int is %d' % (str(value), int(value))
...     except ValueError as ex:
...         print '"%s" cannot be converted to an int: %s' % (value, ex)
...
12345 as an int is 12345
67890 as an int is 67890
3.14 as an int is 3
42 as an int is 42
21 as an int is 21
254 as an int is 254
"Not convertible" cannot be converted to an int: invalid literal for int() with base 10: 'Not convertible'

在Python 3. x

语法略有改变:

>>> for value in '12345', 67890, 3.14, 42, 0b010101, 0xFE, 'Not convertible':
...     try:
...         print('%s as an int is %d' % (str(value), int(value)))
...     except ValueError as ex:
...         print('"%s" cannot be converted to an int: %s' % (value, ex))
...
12345 as an int is 12345
67890 as an int is 67890
3.14 as an int is 3
42 as an int is 42
21 as an int is 21
254 as an int is 254
"Not convertible" cannot be converted to an int: invalid literal for int() with base 10: 'Not convertible'

Answer 4

不幸的是，官方文档并没有详细说明可能引发的异常int()；但是，当您使用 时int()，它实际上可能会引发两个异常：TypeError如果该值不是数字或字符串（或字节或字节数组），并且ValueError该值并未真正映射到数字。

你应该管理两者，像这样：

try:
   int_value = int(value)
except (TypeError, ValueError):
    print('Not an integer')