Python中的两个小数？

Question

我正在尝试制作一个计算气缸体积和表面积的程序; 我目前正在编写它的音量部分.但是,在输出屏幕中,有两位小数.表明:

气缸容积为193019.2896193019.2896cm³

为什么有两个？

之后,我试图让程序询问用户用户想要多少小数位(dp).我怎样才能做到这一点？

这是当前的代码:

print("Welcome to the volume and surface area cylinder calculator powered by Python!")
response = input("To calculate the volume type in 'vol', to calculate the surface area, type in 'SA': ")
if response=="vol" or response =="SA":
    pass
else:
    print("Please enter a correct statement.")
    response = input("To calculate the volume type in 'vol', to calculate the surface area, type in 'SA': ")

if response=="vol":
    #Below splits 
    radius, height = [float(part) for part in input("What is the radius and height of the cylinder? (e.g. 32, 15): ").split(',')] 
    PI = 3.14159 #Making the constant PI
    volume = PI*radius*radius*height
    print("The volume of the cylinder is" + str(volume) + "{}cm\u00b3".format(volume))

Answer 1

您正在两次插值:

print("The volume of the cylinder is" + str(volume) + "{}cm\u00b3".format(volume))

只需一次就可以:

print("The volume of the cylinder is {}cm\u00b3".format(volume))

关于该.format()函数的好处是你可以告诉它将你的数字格式化为一定数量的小数:

print("The volume of the cylinder is {:.5f}cm\u00b3".format(volume))

它将使用5位小数.该数字也可以参数化:

decimals = 5
print("The volume of the cylinder is {0:.{1}f}cm\u00b3".format(volume, decimals))

演示:

>>> volume = 193019.2896
>>> decimals = 2
>>> print("The volume of the cylinder is {0:.{1}f}cm\u00b3".format(volume, decimals))
The volume of the cylinder is 193019.29cm³
>>> decimals = 3
>>> print("The volume of the cylinder is {0:.{1}f}cm\u00b3".format(volume, decimals))
The volume of the cylinder is 193019.290cm³

我将离开使用input()并向int()用户询问整数个小数.