{"id":3448,"date":"2025-06-03T14:54:12","date_gmt":"2025-06-04T07:43:12","guid":{"rendered":"https:\/\/badgameshow.com\/steven\/?p=3448"},"modified":"2025-06-04T14:54:12","modified_gmt":"2025-06-04T07:43:12","slug":"%e4%ba%86%e8%a7%a3python%e4%b8%ad%e7%9a%84getitem%e5%8a%9f%e8%83%bd","status":"publish","type":"post","link":"https:\/\/badgameshow.com\/steven\/python\/%e4%ba%86%e8%a7%a3python%e4%b8%ad%e7%9a%84getitem%e5%8a%9f%e8%83%bd\/","title":{"rendered":"\u6df1\u5165\u4e86\u89e3 Python \u4e2d\u7684 `__getitem__()` \u65b9\u6cd5\uff1a\u4f7f\u7528\u6280\u5de7\u8207\u5be6\u4f5c\u7bc4\u4f8b"},"content":{"rendered":"

<\/p>\n

Python \u4e2d\u7684 __getitem__() \u65b9\u6cd5<\/h1>\n

Python \u4e2d\u7684 `__getitem__()` \u65b9\u6cd5\u662f\u4e00\u500b\u975e\u5e38\u6709\u7528\u7684\u51fd\u5f0f\uff0c\u5b83\u5141\u8a31\u4f60\u5f9e\u53ef\u8fed\u4ee3\u7684\u7269\u4ef6\u4e2d\u7372\u53d6\u6307\u5b9a\u5143\u7d20\u3002\u9019\u500b\u65b9\u6cd5\u9069\u7528\u65bc\u5b57\u5178\u3001\u5217\u8868\u3001\u5143\u7d44\u7b49\u591a\u7a2e\u53ef\u8fed\u4ee3\u7269\u4ef6\uff0c\u80fd\u5920\u6709\u6548\u5730\u63d0\u5347\u8cc7\u6599\u5b58\u53d6\u7684\u6548\u7387\u8207\u4fbf\u6377\u6027\u3002<\/p>\n

__getitem__() \u7684\u57fa\u672c\u7528\u6cd5<\/h2>\n

`__getitem__()` \u65b9\u6cd5\u7684\u57fa\u672c\u7528\u6cd5\u662f\u5c07\u5e0c\u671b\u53d6\u5f97\u7684\u5143\u7d20\u7684\u7d22\u5f15\u503c\u6216\u9375\u503c\u4f5c\u70ba\u53c3\u6578\u50b3\u5165\uff0c\u9019\u6a23\u4fbf\u80fd\u5feb\u901f\u53d6\u5f97\u5c0d\u61c9\u7684\u5143\u7d20\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u5f9e\u5217\u8868\u4e2d\u53d6\u5f97\u7d22\u5f15\u503c\u70ba 3 \u7684\u5143\u7d20\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u7684\u7a0b\u5f0f\u78bc\uff1a<\/p>\n

“`python
\nmy_list = [1, 2, 3, 4, 5]\nelement = my_list[3] # \u4f7f\u7528\u7d22\u5f15\u76f4\u63a5\u53d6\u503c
\nprint(element) # \u8f38\u51fa: 4
\n“`<\/p>\n

\u503c\u5f97\u6ce8\u610f\u7684\u662f\uff0c`__getitem__()` \u5176\u5be6\u662f\u900f\u904e\u65b9\u62ec\u865f `[]` \u4f86\u8abf\u7528\u7684\uff0c\u9019\u662f Python \u5c0d\u5e95\u5c64\u65b9\u6cd5\u7684\u5c01\u88dd\u3002\u57f7\u884c\u4e0a\u9762\u7684\u7a0b\u5f0f\u78bc\uff0c\u53ef\u4ee5\u5f97\u5230\u5217\u8868\u4e2d\u7d22\u5f15\u503c\u70ba 3 \u7684\u5143\u7d20\uff0c\u5373 4\u3002<\/p>\n

__getitem__() \u5728\u5b57\u5178\u4e2d\u7684\u61c9\u7528<\/h2>\n

`__getitem__()` \u65b9\u6cd5\u5728\u5b57\u5178\u4e2d\u540c\u6a23\u9069\u7528\uff0c\u53ef\u4ee5\u7528\u65bc\u53d6\u5f97\u7279\u5b9a\u9375\u6240\u5c0d\u61c9\u7684\u503c\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u53d6\u5f97\u5b57\u5178\u4e2d\u9375\u70ba “name” \u7684\u5143\u7d20\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u7684\u7a0b\u5f0f\u78bc\uff1a<\/p>\n

“`python
\nmy_dict = {
\n “name”: “John”,
\n “age”: 20
\n}
\nname = my_dict[“name”] # \u4f7f\u7528\u9375\u76f4\u63a5\u53d6\u503c
\nprint(name) # \u8f38\u51fa: John
\n“`<\/p>\n

\u9019\u6a23\u7684\u5beb\u6cd5\u4f7f\u5f97\u8cc7\u6599\u5b58\u53d6\u66f4\u52a0\u76f4\u89c0\u8207\u7c21\u6f54\u3002<\/p>\n

\u591a\u7dad\u5ea6\u8cc7\u6599\u7d50\u69cb\u7684\u5b58\u53d6<\/h2>\n

`__getitem__()` \u4e5f\u53ef\u4ee5\u7528\u65bc\u591a\u7dad\u5ea6\u7684\u53ef\u8fed\u4ee3\u7269\u4ef6\u4e2d\uff0c\u4f8b\u5982\u4e8c\u7dad\u5217\u8868\u3002\u4ee5\u4e0b\u662f\u53d6\u5f97\u4e8c\u7dad\u5217\u8868\u4e2d\u67d0\u500b\u5143\u7d20\u7684\u7bc4\u4f8b\uff1a<\/p>\n

“`python
\nmy_matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]\nelement = my_matrix[1][2] # \u53d6\u5f97\u7b2c\u4e8c\u884c\u7b2c\u4e09\u5217\u7684\u5143\u7d20
\nprint(element) # \u8f38\u51fa: 6
\n“`<\/p>\n

\u9019\u6a23\u7684\u65b9\u5f0f\u53ef\u4ee5\u8f15\u9b06\u5730\u5b58\u53d6\u5230\u8907\u96dc\u8cc7\u6599\u7d50\u69cb\u4e2d\u7684\u7279\u5b9a\u5143\u7d20\u3002<\/p>\n

\u932f\u8aa4\u6392\u9664\u8207\u6700\u4f73\u5be6\u8e10<\/h2>\n

\u4f7f\u7528 `__getitem__()` \u65b9\u6cd5\u6642\uff0c\u53ef\u80fd\u6703\u9047\u5230\u4ee5\u4e0b\u5e7e\u7a2e\u5e38\u898b\u932f\u8aa4\uff1a<\/p>\n

1. **\u7d22\u5f15\u932f\u8aa4\uff08IndexError\uff09**\uff1a\u7576\u7d22\u5f15\u8d85\u51fa\u7bc4\u570d\u6642\uff0c\u6703\u5f15\u767c\u6b64\u932f\u8aa4\u3002\u78ba\u4fdd\u7d22\u5f15\u503c\u5728\u6709\u6548\u7bc4\u570d\u5167\u3002
\n2. **\u9375\u932f\u8aa4\uff08KeyError\uff09**\uff1a\u7576\u67e5\u8a62\u7684\u9375\u5728\u5b57\u5178\u4e2d\u4e0d\u5b58\u5728\u6642\uff0c\u5c07\u5f15\u767c\u6b64\u932f\u8aa4\u3002\u53ef\u4ee5\u4f7f\u7528 `dict.get()` \u65b9\u6cd5\u4f86\u907f\u514d\u6b64\u554f\u984c\u3002<\/p>\n

\u6700\u4f73\u5be6\u8e10\u5efa\u8b70\uff1a
\n– \u4f7f\u7528 `try-except` \u584a\u4f86\u6355\u7372\u53ef\u80fd\u7684\u932f\u8aa4\uff0c\u4ee5\u63d0\u5347\u7a0b\u5f0f\u7684\u5065\u58ef\u6027\u3002
\n– \u5118\u91cf\u4f7f\u7528\u660e\u78ba\u7684\u7d22\u5f15\u6216\u9375\u540d\u4f86\u589e\u52a0\u7a0b\u5f0f\u7684\u53ef\u8b80\u6027\u3002<\/p>\n

\u5ef6\u4f38\u61c9\u7528<\/h2>\n

`__getitem__()` \u65b9\u6cd5\u4e0d\u50c5\u9650\u65bc\u57fa\u672c\u7684\u8cc7\u6599\u7d50\u69cb\uff0c\u4e5f\u53ef\u4ee5\u7528\u65bc\u81ea\u5b9a\u7fa9\u985e\u5225\u4e2d\u3002\u4f60\u53ef\u4ee5\u901a\u904e\u5be6\u4f5c `__getitem__()` \u65b9\u6cd5\uff0c\u8b93\u81ea\u5b9a\u7fa9\u985e\u5225\u5177\u6709\u985e\u4f3c\u5217\u8868\u6216\u5b57\u5178\u7684\u7d22\u5f15\u5b58\u53d6\u884c\u70ba\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u7c21\u55ae\u7684\u7bc4\u4f8b\uff1a<\/p>\n

“`python
\nclass CustomList:
\n def __init__(self, initial_data):
\n self.data = initial_data<\/p>\n

def __getitem__(self, index):
\n return self.data[index]\n

custom_list = CustomList([10, 20, 30])
\nprint(custom_list[1]) # \u8f38\u51fa: 20
\n“`<\/p>\n

\u9019\u6a23\u7684\u65b9\u5f0f\u4f7f\u5f97\u4f60\u7684\u985e\u5225\u53ef\u4ee5\u66f4\u52a0\u9748\u6d3b\u8207\u6613\u65bc\u4f7f\u7528\u3002<\/p>\n

\u53c3\u8003\u8cc7\u6599<\/h2>\n