split函数的实现

def simu_split(sep):
    s1="www  neu   edu    cn"
    #s1=s1.strip()
    length=len(s1)
    print length
    a=s1.find(sep)
    n=len(sep)
    if a==-1:
        print s1
    elif:
        print s1[:a],
    while a<length and a!=-1:
        
        while a<length and s1[a:a+n]==sep ://这一步跟标准库的处理不同，标准库是遇到一个
                                                            //sep就打印
            a+=n
        b=a
        a=s1.find(sep,b)
        if a==-1:
            print s1[b:length],
        else:
            print s1[b:a],
    else:
        print "\nelse"
    print "out of while"
simu_split(" ")
print "end of the file"