python - 删除第一个和最后一个特定符号

Question

如何从输入文本中删除第一个和最后一个“i ”？第一个变体删除文本最后一个字母和重复项:

Entered TexEntered Text
          ^           ^

第二个变体什么也不做。

代码:

txt4 = input("Enter text: ")
txt4 = txt4.swapcase()
print(txt4)
x = "I" or "i"
x1 = txt4.find(x)
x2 = txt4.rfind(x)
if [x1, x2] == -1:
    print("Letter \"i\" not found!")
else:
    #txt4 = txt4.replace(txt4[0:(x1+1)], "", 1) #]
    #txt4 = txt4.replace(txt4[(x2):0], "", 1)   #]-2nd variant
    #txt4x1 = txt4[:(x1+1)] + txt4[(x2):]       #]
    txt4x1 = txt4[0:x1]+txt4[(x1+1):]
    txt4x1 = txt4[0:x2]+txt4[(x2+1):]
    print(txt4x1)

Answer 1

您可以使用正则表达式:

import re
regex = re.compile('i', flags=re.IGNORECASE)
txt = input("Enter text: ")
# re.sub() always searches from left, so we reverse txt using slice [::-1]
# to find the last match. Then we flip it again.
txt = regex.sub('', txt[::-1], 1)
txt = regex.sub('', txt[::-1], 1)
print(txt)

另一种更短的方法来完成同样的事情。

txt = input("Enter text: ")
for direction in 'from right', 'from left':  # do it twice
     txt = re.sub('[iI]', '', txt[::-1], count=1)
print(txt)