message = input("Please tell me your name:") print("Hello , " + message + "!")
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输出结果如下：
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1 2
Please tell me your name:anliy Hello , anliy!
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进阶：
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message = "Please tell me your name so that we can personalize the messages you see." message += "\nWhat's your first name?" name = input(message) print("\nHello , " + name + "!")
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输出结果如下：
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Please tell me your name so that we can personalize the messages you see. What's your first name?trhx Hello , trhx!
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- 6.1.1 使用 int() 来获取数值输入
使用函数 input() 时，Python会将用户输入解读为字符串：
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>>> age = input("How old are you?") How old are you?19 >>> age '19'
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为了解决这个问题，可以使用函数 int() ，它让Python将输入视为数值：
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>>> age = input("How old are you?") How old are you?19 >>> age = int(age) >>> age 19
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实例：
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age = input("Please tell me your age:") age = int(age) if age >= 18: print("You are old enough to go to the Internet bar!") else: print("You are not old enough to go to Internet bar!")
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输出结果如下：
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1 2
Please tell me your age:17 You are not old enough to go to Internet bar!
for 循环用于针对集合中的每一个元素的一个代码块，而 while 循环不断地运行，直到指定的条件不满足为止
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- 6.2.1 使用 while 循环
一个简单的 while 循环：
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num = 1 while num < 5: print(num) num += 1
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输出结果如下：
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1 2 3 4
1 2 3 4
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- 6.2.2 让用户选择退出循环
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prompt = "\nTell me something, and I will repeat it back to you:" prompt += "\nEnter 'quit' to end the program." message = " " while message != 'quit': message = input(prompt) print(message)
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运行程序：
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Tell me something, and I will repeat it back to you: Enter 'quit' to end the program.Hello everyone! Hello everyone!
Tell me something, and I will repeat it back to you: Enter 'quit' to end the program.Hello again! Hello again!
Tell me something, and I will repeat it back to you: Enter 'quit' to end the program.quit quit
prompt = "\nTell me something, and I will repeat it back to you:" prompt += "\nEnter 'quit' to end the program." active = True while active: message = input(prompt) if message == 'quit': active = False else: print(message)
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运行结果与6.2.2一致
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- 6.2.4 使用 break 退出循环
要立即退出 while 循环，不再运行循环中余下的代码，也不管条件测试的结果如何，可使用 break 语句，break 语句用于控制程序流程，可使用它来控制哪些代码将执行，哪些代码不执行
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prompt = "\nPlease enter the name of a city you have visited:" prompt += "\nEnter 'quit' when you are finished." active = True while active: city = input(prompt) if city == 'quit': break else: print("I'd love to go to " + city.title() + "!")
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运行程序：
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Please enter the name of a city you have visited: Enter 'quit' when you are finished.Shanghai I'd love to go to Shanghai! Please enter the name of a city you have visited: Enter 'quit' when you are finished.Beijing I'd love to go to Beijing!
Please enter the name of a city you have visited: Enter 'quit' when you are finished.quit
while polling_active: #提示输入被调查者的姓名和回答 name = input("\nWhat's your name?") response = input("What kind of fruit do you like?") #将答卷储存在字典中 responses[name] = response #询问是否还有其他人要参与回答 repeat = input("Would you like to let another person respond?(Yes/No)") if repeat == 'No': polling_active = False
#调查结束，显示结果 print("\n------ Poll Results ------") for name , response in responses.items(): print(name + " like " + response + ".")
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运行程序：
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What's your name?TRHX What kind of fruit do you like?apple Would you like to let another person respond?(Yes/No)Yes What's your name?TRHXCC What kind of fruit do you like?banana Would you like to let another person respond?(Yes/No)No
------ Poll Results ------ TRHX like apple. TRHXCC like banana.
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