如何允许用户在计算器中的操作中不输入数字

Question

这是我在Python中的第三个项目。我正在做计算器，我有所有的运算等等，工作得很好。然而，我希望用户不必在其中两个运算中输入第二个数字(即欧拉数和圆周率(，计算器仍然可以工作。例如，如果我想把一个数字乘以π，现在，我需要输入"1"作为第二个数字。我想消除这种需要。我真的很感激你能提供的任何帮助。

import math

def welcome():
print('''
Welcome to Calculator
''')

# Define our function
welcome()

def calculate():
operation = input('''
Please type in the math operation you would like to complete:
+ for addition
- for subtraction
* for multiplication
/ for division
** for power
% for modulo
pi to multiply by Pi 
e to multiply by Euler's Number 
''')
number_1 = float(input('Please enter the first number: '))
number_2 = float(input('Please enter the second number: '))
if operation == 'e':
print('{} * e = '.format(number_1, math.e))
print(number_1 * math.e)
elif operation == 'pi':
print('{} * Pi = '.format(number_1, math.pi))
print(number_1 * math.pi)
elif operation == '+':
print('{} + {} = '.format(number_1, number_2))
print(number_1 + number_2)
elif operation == '-':
print('{} - {} = '.format(number_1, number_2))
print(number_1 - number_2)
elif operation == '*':
print('{} * {} = '.format(number_1, number_2))
print(number_1 * number_2)
elif operation == '/':
print('{} / {} = '.format(number_1, number_2))
print(number_1 / number_2)
elif operation == '**':
print('{} ** {} ='.format(number_1, number_2))
print(number_1 ** number_2)
elif operation == '%':
print('{} % {} ='.format(number_1, number_2))
print(number_1 % number_2)
else:
print('You have not typed a invalid operator, please run the program again.')
# Add again() function to calculate() function
again()

def again():
calc_again = input('''
Do you want to calculate again?
Please type Y for YES or N for NO.
''')
if calc_again.upper() == 'Y':
calculate()
elif calc_again.upper() == 'N':
print("Thank you for using the calculator. I'll be here whenever you need me.")
else:
again()

# Call calculate() outside of the function
calculate()

Answer 1

专注于您需要更改的特定片段，这里有一种方法：

...
number_1 = float(input('Please enter a number: '))
if operation == 'e' or operation == 'pi':
if operation == 'e':
print('{} * e = '.format(number_1, math.e))
print(number_1 * math.e)
elif operation == 'pi':
print('{} * Pi = '.format(number_1, math.pi))
print(number_1 * math.pi)
else:
number_2 = float(input('Please enter a second number: '))
if operation == '+':
print('{} + {} = '.format(number_1, number_2))
print(number_1 + number_2)
elif operation == '-':
print('{} - {} = '.format(number_1, number_2))
print(number_1 - number_2)
...

Answer 2

只需在上添加一个if条件

number_2 = float(input('Please enter the second number: '))

像这个

if(operation != 'e' || operation != 'pi'):
number_2 = float(input('Please enter the second number: '))

Answer 3

在对e和pi进行条件检查后，通过将第二个数字的输入移动到所有循环中，可以在不对代码进行太多更改的情况下解决此问题。

例如：

number_1 = float(input('Please enter the first number: '))
if operation == 'e':
print('{} * e = '.format(number_1, math.e))
print(number_1 * math.e)
elif operation == 'pi':
print('{} * Pi = '.format(number_1, math.pi))
print(number_1 * math.pi)
elif operation == '+':
number_2 = float(input('Please enter the second number: '))
print('{} + {} = '.format(number_1, number_2))
print(number_1 + number_2)

这不遵循最佳实践，但应该按照您的意愿进行。如果你想要一种比这更好的方法，我可以编辑这个答案，包括改进之处以及为什么它们更好。