在字符串中逐个字符并用python交换空格

Question

好吧，我得换成s了。我想到了以下几点

def characterSwitch(ch,ca1,ca2,start = 0, end = len(ch)):
    while start < end:
        if ch[start] == ca1:
            ch[end] == ca2
        start = start + 1
sentence = "Ceci est une toute petite phrase."
print characterSwitch(sentence, ' ', '*')
print characterSwitch(sentence, ' ', '*', 8, 12)
print characterSwitch(sentence, ' ', '*', 12)
print characterSwitch(sentence, ' ', '*', end = 12)

分配len（ch）似乎不起作用，而且我很确定这不是最有效的方法。以下是我的目标输出：

Ceci*est*une*toute*petite*phrase.
Ceci est*une*toute petite phrase.
Ceci est une*toute*petite*phrase.
Ceci*est*une*toute petite phrase.

Answer 1

假设你必须一个字符一个字符地做，你可以这样做：

sentence = "this is a sentence."
replaced = ""

for c in sentence:
    if c == " ":
        replaced += "*"
    else:
        replaced += c

print replaced