Python基礎：列表遍歷

2024年12月06日07:23:14 教育 1745

遍歷整個列表：

For 循環：

使用列表項自動執行重複性任務。
示例： for magician in magicians: print(magician) .

magicians = ['Alice', 'David', 'carolina']
 for magician in magicians:
    print(magician)

>>

alice
 david
 carolina

迭代所有項：

Loop 檢索並處理每個項目。
示例：在列表中列印每個魔術師的名字。

magicians = ['alice', 'david', 'carolina']
 for magician in magicians:
    print(f"{magician.title()}, that was a great trick!")

>>

 Alice, that was a great trick!
 David, that was a great trick!
 Carolina, that was a great trick!

循環執行：

對每個列表項重複上述步驟。
示例：使用循環的個性化消息。

magicians = ['alice', 'david', 'carolina']
 for magician in magicians:
    print(f"{magician.title()}, that was a great trick!")
    print(f"I can't wait to see your next trick, {magician.title()}.\n")

>>

Alice, that was a great trick!
I can't wait to see your next trick, Alice.

David, that was a great trick!
I can't wait to see your next trick, David.

Carolina, that was a great trick!
I can't wait to see your next trick, Carolina.

循環後操作：

循環後的代碼執行一次。
示例：在單獨消息後感謝所有魔術師。

magicians = ['alice', 'david', 'carolina']
 for magician in magicians:
    print(f"{magician.title()}, that was a great trick!")
    print(f"I can't wait to see your next trick, {magician.title()}.\n")
 print("Thank you, everyone. That was a great magic show!")


>>

Alice, that was a great trick!
 I can't wait to see your next trick, Alice.

 David, that was a great trick!
I can't wait to see your next trick, David.

 Carolina, that was a great trick!
 I can't wait to see your next trick, Carolina.

 Thank you, everyone. That was a great magic show!

避免 Python 中的縮進錯誤

忘記縮進：

magicians = ['alice', 'david', 'carolina']
for magician in magicians:
print(magician)  # Should be indented

#Error : 
File "magicians.py", line 3
    print(magician)
    ^
 IndentationError: expected an indented block after 'for' statement on line 2

錯誤： IndentationError: expected an indented block after 'for' statement
修復：縮進 print（magician）行。

忘記縮進額外的行：

for magician in magicians:
    print(f"{magician.title()}, that was a great trick!")
print(f"I can't wait to see your next trick, {magician.title()}.\n")  # Should be indented


#OutPut

Alice, that was a great trick!
 David, that was a great trick!
 Carolina, that was a great trick!
 I can't wait to see your next trick, Carolina.

問題：只有最後一個魔術師會收到第二條消息，因為該行不在循環內。
修復：縮進第二個 print 語句。

不必要地縮進：

message = "Hello Python world!"
    print(message)  # Unnecessary indent

#Error : 

File "hello_world.py", line 2
    print(message)
    ^
 IndentationError: unexpected indent

錯誤： IndentationError: unexpected indent
修復：刪除不必要的縮進。

在循環後縮進：

for magician in magicians:
    print(f"{magician.title()}, that was a great trick!")
    print(f"I can't wait to see your next trick, {magician.title()}.\n")
    print("Thank you everyone, that was a great magic show!")  # Should not be indented


>>

Alice, that was a great trick!
I can't wait to see your next trick, Alice.
Thank you everyone, that was a great magic show!

 David, that was a great trick!
 I can't wait to see your next trick, David.
 Thank you everyone, that was a great magic show!

 Carolina, that was a great trick!
 I can't wait to see your next trick, Carolina.
 Thank you everyone, that was a great magic show

問題：感謝信息是為每位魔術師列印的。
修復：取消縮進最後一個 print 語句。

忘記冒號：

for magician in magicians  # Missing colon
    print(magician)


#Error : 

 File "magicians.py", line 2
    for magician in magicians
                             ^
 SyntaxError: expected ':'