Str.isdigit()应该可以做到这一点。

例子:

str.isdigit("23") ## True
str.isdigit("abc") ## False
str.isdigit("23.4") ## False

编辑: 正如@BuzzMoschetti指出的那样，这种方法对于负数(例如“-23”)将失败。如果您的input_num可以小于0，请在应用str.isdigit()之前使用re.sub(regex_search,regex_replace,contents)。例如:

import re
input_num = "-23"
input_num = re.sub("^-", "", input_num) ## "^" indicates to remove the first "-" only
str.isdigit(input_num) ## True

正确的RegEx解决方案应该结合Greg Hewgill和Nowell的思想，但不使用全局变量。可以通过将属性附加到方法来实现这一点。另外，我知道在方法中导入是不受欢迎的，但我想要的是像http://peak.telecommunity.com/DevCenter/Importing#lazy-imports这样的“惰性模块”效果

edit:到目前为止，我最喜欢的技术是使用String对象的独占方法。

#!/usr/bin/env python

# Uses exclusively methods of the String object
def isInteger(i):
    i = str(i)
    return i=='0' or (i if i.find('..') > -1 else i.lstrip('-+').rstrip('0').rstrip('.')).isdigit()

# Uses re module for regex
def isIntegre(i):
    import re
    if not hasattr(isIntegre, '_re'):
        print("I compile only once. Remove this line when you are confident in that.")
        isIntegre._re = re.compile(r"[-+]?\d+(\.0*)?$")
    return isIntegre._re.match(str(i)) is not None

# When executed directly run Unit Tests
if __name__ == '__main__':
    for obj in [
                # integers
                0, 1, -1, 1.0, -1.0,
                '0', '0.','0.0', '1', '-1', '+1', '1.0', '-1.0', '+1.0',
                # non-integers
                1.1, -1.1, '1.1', '-1.1', '+1.1',
                '1.1.1', '1.1.0', '1.0.1', '1.0.0',
                '1.0.', '1..0', '1..',
                '0.0.', '0..0', '0..',
                'one', object(), (1,2,3), [1,2,3], {'one':'two'}
            ]:
        # Notice the integre uses 're' (intended to be humorous)
        integer = ('an integer' if isInteger(obj) else 'NOT an integer')
        integre = ('an integre' if isIntegre(obj) else 'NOT an integre')
        # Make strings look like strings in the output
        if isinstance(obj, str):
            obj = ("'%s'" % (obj,))
        print("%30s is %14s is %14s" % (obj, integer, integre))

对于那些不太喜欢冒险的同学，输出如下:

I compile only once. Remove this line when you are confident in that.
                             0 is     an integer is     an integre
                             1 is     an integer is     an integre
                            -1 is     an integer is     an integre
                           1.0 is     an integer is     an integre
                          -1.0 is     an integer is     an integre
                           '0' is     an integer is     an integre
                          '0.' is     an integer is     an integre
                         '0.0' is     an integer is     an integre
                           '1' is     an integer is     an integre
                          '-1' is     an integer is     an integre
                          '+1' is     an integer is     an integre
                         '1.0' is     an integer is     an integre
                        '-1.0' is     an integer is     an integre
                        '+1.0' is     an integer is     an integre
                           1.1 is NOT an integer is NOT an integre
                          -1.1 is NOT an integer is NOT an integre
                         '1.1' is NOT an integer is NOT an integre
                        '-1.1' is NOT an integer is NOT an integre
                        '+1.1' is NOT an integer is NOT an integre
                       '1.1.1' is NOT an integer is NOT an integre
                       '1.1.0' is NOT an integer is NOT an integre
                       '1.0.1' is NOT an integer is NOT an integre
                       '1.0.0' is NOT an integer is NOT an integre
                        '1.0.' is NOT an integer is NOT an integre
                        '1..0' is NOT an integer is NOT an integre
                         '1..' is NOT an integer is NOT an integre
                        '0.0.' is NOT an integer is NOT an integre
                        '0..0' is NOT an integer is NOT an integre
                         '0..' is NOT an integer is NOT an integre
                         'one' is NOT an integer is NOT an integre
<object object at 0x103b7d0a0> is NOT an integer is NOT an integre
                     (1, 2, 3) is NOT an integer is NOT an integre
                     [1, 2, 3] is NOT an integer is NOT an integre
                {'one': 'two'} is NOT an integer is NOT an integre

如果你真的不喜欢到处使用try/except，请写一个helper函数:

def represents_int(s):
    try: 
        int(s)
    except ValueError:
        return False
    else:
        return True

>>> print(represents_int("+123"))
True
>>> print(represents_int("10.0"))
False

它将需要更多的代码来精确覆盖Python认为是整数的所有字符串。要我说，你就用蟒语吧。

Greg Hewgill的方法缺少了几个组件:前导的“^”只匹配字符串的开头，并且预先编译re。但是这种方法可以让你避免尝试:

import re
INT_RE = re.compile(r"^[-]?\d+$")
def RepresentsInt(s):
    return INT_RE.match(str(s)) is not None

我很感兴趣为什么你试图避免尝试:除了?

>>> "+7".lstrip("-+").isdigit()
True
>>> "-7".lstrip("-+").isdigit()
True
>>> "7".lstrip("-+").isdigit()
True
>>> "13.4".lstrip("-+").isdigit()
False

所以你的函数是

def is_int(val):
   return val.lstrip("-+").isdigit()

据我所知，你想检查字符串可转换的int。要做到这一点你可以:

将'-'替换为空，因为'-'不是数字和'-7'也可以转换为int。 检查一下是不是数字。

def is_string_convertable_to_int(value: str) -> bool:
    return value.replace('-', '').isdigit()

另外，你可以很容易地修改这个def来检查字符串在float中的可转换性，只需添加replace('。'， ")，并检查一个'。'使用value.count('.') = 1存在。