python判断字符串是否纯数字代码

#!/usr/bin/python
# -*- coding: utf-8 -*-

a = "1"
b = "1.2"
c = "a"
#通过抛出异常
def is_num_by_except(num):
    try:
        int(num)
        return True
    except ValueError:
#        print "%s ValueError" % num
        return False

print "通过抛出异常"
print "a", is_num_by_except(a)   
print "b", is_num_by_except(b)
print "c", is_num_by_except(c)

print "通过isdigit()"
print "a", a.isdigit()
print "b", b.isdigit()
print "c", c.isdigit()

print "通过正则表达式"
import re
print "a", re.match(r"d+$", a) and True or False
print "b", re.match(r"d+$", b) and True or False
print "c", re.match(r"d+$", c) and True or False
输出结果如下:

通过抛出异常
a True
b False
c False
通过isdigit()
a True
b False
c False
通过正则表达式
a True
b False
c False
--EOF--

try:
    x = int(aPossibleInt)
    … do something with x …
except ValueError:
    … do something else …

re.match(r’[+-]?d+$’, ‘-1234′)