Question

我正在为法语写一个程序，将现在时态的动词变成过去时。问题是我需要替换字母，但他们是用户输入的，所以我必须让它替换行末尾的字母。这是我到目前为止所拥有的，但它并没有改变它只是给出错误的字母：

word = raw_input("what words do you want to turn into past tense?")
word2= word

if word2.endswith("re"):
 word3 = word2.replace('u', 're')
 print word3

elif word2.endswith("ir"):
 word2[-2:] = "i"
 print word2

elif word2.endswith("er"):
 word2[-2:] = "e"
 print word2

else:
 print "nope"

我尝试了单词替换，这也没有用，它只是给了我相同的字符串。如果有人可以给我一个例子，也许可以解释一下那会很棒。：/

Answer 1

IMO可能存在使用替换方式的问题。解释了替换的语法。 here

string.replace(s, old, new[, maxreplace])

这个ipython会话可能会帮助你。

In [1]: mystring = "whatever"

In [2]: mystring.replace('er', 'u')
Out[2]: 'whatevu'

In [3]: mystring
Out[3]: 'whatever'

基本上你想要替换的模式首先出现，然后是你要替换的字符串。

Answer 2

对不起

word3 = word2.replace('u', 're')

上面的行代码可能会产生错误的结果，因为
在你的话中可能存在另一个“呃”

Answer 3

String是不可变的，所以你不能只替换最后2个字母......你必须从existant中创建一个新的字符串。

并且正如MM-BB所说，替换将取代信件的所有信息......

试

word = raw_input("what words do you want to turn into past tense?")
word2 = word

if word2.endswith("re"):
    word3 = word2[:-2] + 'u'
    print word3

elif word2.endswith("ir"):
    word3 = word2[:-2] + "i"
    print word3

elif word2.endswith("er"):
    word3 = word2[:-2] + "e"
    print word3

else:
    print "nope"

前1：

what words do you want to turn into past tense?sentir
senti

前2：

what words do you want to turn into past tense?manger
mange

Answer 4

我认为正则表达式在这里是更好的解决方案，特别是subn方法。

import re

word = 'sentir'

for before, after in [(r're$','u'),(r'ir$','i'),(r'er$','e')]:
    changed_word, substitutions  = re.subn(before, after, word)
    if substitutions:
        print changed_word
        break
else:
    print "nope"

Answer 5

essentially what you've done wrong is "word2.replace('u', 're')" This means that you are replace 'u' with 're' inside the var word2. I have changed the code;

 word = raw_input("what words do you want to turn into past tense?")
 word2= word

 if word2.endswith("re"):
    word3 = word2.replace('re', 'u')
    print word3

  elif word2.endswith("ir"):
     word2[-2:] = "i"
     print word2

 elif word2.endswith("er"):
    word2[-2:] = "e"
    print word2

 else:
     print "nope"

替换python字符串中的字母

5 个答案: