replace函数实现

##replace函数，跟split函数处理类似，比split简单

#coding=gbk

ss='** *axx*  *bv** *ctt**   **dff***'    
print(ss)
result=[]

def replace_1(s,a,dd,times=None):
    i=0
    n=0   #记录替换次数，对应判断times
    result=[]
    if times==None:
        times=len(s)
    while i<len(s) and len(s)!=0 and n<times:
        if s[i:i+len(a)]==a:
            result+=list(s[0:i])+list(dd)
            s=s[i+len(a):]
            n+=1
            i=0
        else:
            i+=1
    result.append(s)
    return ''.join(result)

print('替换后的结果为：',replace_1(ss,' ','hhh'))