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創(chuàng)新互聯(lián)Python教程：Python中字符串如何查找？
在Python使用字符串的過(guò)程中，如果遇到很多的字符串，想要查找到想要的字符串有些困難。本文主要介紹Python字符串查找的幾種方法：find方法、 index方法、rfind方法、rindex方法。具體請(qǐng)看如下內(nèi)容：
find方法
find方法獲取值時(shí)，如果要查找的值不存在，會(huì)返回-1
str.find(str, beg=0, end=len(string))
使用實(shí)例
# string in which we have to find the sub_string str = "Hello world, how are you?" # sub_string to find the given string sub_str = "how" # find by sub_str print (str.find (sub_str)) # find by sub_str with slice:start index print (str.find (sub_str, 10)) # find by sub_str with slice:start index and slice: end index print (str.find (sub_str, 10, 24)) # find a sub_str that does not exist sub_str = "friend" # find by sub_str print (str.find (sub_str)) # find a sub_str with different case sub_str = "HOW" # find by sub_str print (str.find (sub_str))
輸出
13 13 13 -1 -1
index方法
在獲取值得索引時(shí)，如果不存在值，會(huì)報(bào)錯(cuò)
str.index(str, beg=0, end=len(string))
使用實(shí)例
def second_index(text: str, symbol: str):
"""
returns the second index of symbol in a given text
"""
try:
return text.index(symbol, text.index(symbol) + 1)
except ValueError:
return None
if __name__ == '__main__':
#These "asserts" using only for self-checking and not necessary for auto-testing
print('Example:')
print(second_index("sims", "s"))
assert second_index("sims", "s") == 3, "First"
assert second_index("find the river", "e") == 12, "Second"
assert second_index("hi", " ") is None, "Third"
assert second_index("hi mayor", " ") is None, "Fourth"
assert second_index("hi mr Mayor", " ") == 5, "Fifth"
print('You are awesome! All tests are done! Go Check it!')注意：
find()和index()只能找到第一個(gè)索引值。如果指定字符同時(shí)存在多個(gè)，只會(huì)輸出第一個(gè)指定字符的索引值。
rfind和rindex方法用法和上面一樣，只是從字符串的末尾開(kāi)始查找。
以上就是Python中字符串查找的方法，大家可以選擇符合自己需求的方法來(lái)解決問(wèn)題哦~希望能解決你的問(wèn)題。
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文章源于：http://www.5511xx.com/article/cdjopdp.html
