字符串索引

Question

Python 3.5

这是我的代码：

str1 = input("Please enter a full sentence: ").lower()
print("Thank you, You entered:" , str1)

str2 = input("Now please enter a word included in your sentence in anyway you like: ").lower()

if str2 in str1:
    print("That word was found!")
else:
    print("Sorry, that word was not found")

按原样，它将搜索输入的单词（str2），如果在输入（str1（一个句子））中找到它，它会说“该单词已找到”）。如果该单词不在句子中，它将显示“未找到该单词”。

我想开发这个，所以当搜索并找到单词时，它会告诉用户单词 (str2) 在句子 (str1) 中的索引位置。例如：如果我有句子（“I like to code in Python”）并且我搜索单词（“code”），程序应该说“该单词在索引位置找到：4”。

顺便说一句，代码不区分大小写，因为它使用 .lower 将所有单词转换为小写。

如果有人可以给我一些建议，那将非常感激！

Answer 1

print("That word was found at index %i!"% (str1.split().index(str2)))

这将打印 str1 中第一次出现 str2 的索引。
完整代码为：

str1 = input("Please enter a full sentence: ").lower()
print("Thank you, You entered:" , str1)

str2 = input("Now please enter a word included in your sentence in anyway you like: ").lower()

if str2 in str1:
    print("That word was found!")
    print("that word was found in index position: %i!"% (str1.split().index(str2)))

, str1.index(str2))
别的： print("对不起，找不到那个词")

Answer 2

您可以使用 split() 方法：它在字符串值上调用并返回字符串列表。然后使用 index() 方法查找字符串的索引。

str1 = input("Please enter a full sentence: ").lower()
print("Thank you, You entered:" , str1)
str2 = input("Now please enter a word included in your sentence in anyway you like: ").lower()

if str2 in str1:
    a = str1.split() # you create a list
    # printing the word and index a.index(str2)
    print('The ', str2,' was find a the index ', a.index(str2)) 
    print("That word was found!")
else:
    print("Sorry, that word was not found")

Answer 3

你可以用这个替换你的if ... else：

try:
    print("That word was found at index %i!"% (str1.split().index(str2) + 1))
except ValueError:
    print("Sorry, that word was not found")

Answer 4

str2 = 'abcdefghijklmnopqrstuvwxyz'
str1 = 'z'
index = str2.find(str1)
if index != -1:
    print 'That word was found in index position:',index
else:
    print 'That word was not found'

这将打印str2中str1的索引