判断一个整数是否是2整数次幂三种方法

#encode=utf-8

import time

print u"写一个方法判断一个数是否能被2整除"

def whole1(x):

    try:

        n=0

        x=int(x)

        if x<2:

            print u"{0}不是2".format(x)

        while x>1:

            if x%2!=0:

                print u"number不是2整次幂"

                return False

            x/=2.0

            n+=1

        print u"2的{0}次方".format(n)

        return True

    except Exception,e:

        print u"程序出现错误{0[:]}".format(e.message)

 

def whole2(x):

    try:

        x=int(x)

        result="{0:b}".format(x)

        if result.count("1")==1 and result[0]=="1":

            print u"{0}能被2整除".format(x)

        else:

            print u"{0}不能被2整除".format(x)

    except Exception,e:

        print u"程序出现错误{0[:]}".format(e.message)

 

def whole3(x):

    try:

        n=0

        x=int(x)

        if x<2:

            print u"{0}不是2".format(x)

        while x>1:

            if x%2!=0:

                print u"number不是2整次幂"

                return False

            x=x>>1

            n+=1

        print u"2的{0}次方".format(n)

        return True

    except Exception,e:

        print u"程序出现错误{0[:]}".format(e.message)

 

if __name__=="__main__":

    time1=time.time()

    number=raw_input("输入一个整数: ".decode("utf-8").encode("gbk"))

    print "_"*20

    for i in range(1,4):

        print u"第{0}个程序执行结果: ".format(i)

        eval_r("whole{0}".format(i)+"(number)")

    print "_"*20

    print u"程序执行完耗时{0}".format(time.time()-time1)