python怎么定义用户输入

Python中获取用户输入的方法如下：

整数输入

#!/usr/bin/python3
usr_ip = input("Enter an integer number: ")

# 需要将输入的字符串显式地指定为需要的类型

usr_num = int(usr_ip)
sqr_num = usr_num * usr_num
print("Square of entered number is: {}".format(sqr_num))

让我们给定一个整数和字符串来测定这个程序

Python docs - 整数文本

$ ./user_input_int.py
Enter an integer number: 23
Square of entered number is: 529
$ ./user_input_int.py
Enter an integer number: abc
Traceback (most recent call last):
  File "./user_input_int.py", line 6, in <module>
    usr_num = int(usr_ip)
ValueError: invalid literal for int() with base 10: 'abc'

浮点数输入

#!/usr/bin/python3
usr_ip = input("Enter a floating point number: ")
# 需要将输入的字符串显式地指定为我们需要的类型
usr_num = float(usr_ip)
sqr_num = usr_num * usr_num
# 限制小数点位数
print("Square of entered number is: {0:.2f}".format(sqr_num))

E 科学计数法在需要时可以使用

Python文档 - 浮点数文本

Python文档 - 浮点数

$ ./user_input_float.py
Enter a floating point number: 3.232
Square of entered number is: 10.45
$ ./user_input_float.py
Enter a floating point number: 42.7e5
Square of entered number is: 18232900000000.00
$ ./user_input_float.py
Enter a floating point number: abc
Traceback (most recent call last):
  File "./user_input_float.py", line 6, in <module>
    usr_num = float(usr_ip)
ValueError: could not convert string to float: 'abc'

字符串输入

#!/usr/bin/python3
usr_name  = input("Hi there! What's your name? ")
usr_color = input("And your favorite color is? ")
print("{}, I like the {} color too".format(usr_name, usr_color))

不像Perl，字符串输入不需要进行类型转换和注意换行符

$ ./user_input_str.py
Hi there! What's your name? learnbyexample
And your favorite color is? blue
learnbyexample, I like the blue color too

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