如何修复“语法错误，无效语法”（无上下文或原因）Elif Function Python

Question

我的 elif 行上不断出现语法错误（箭头指向“elif”的末尾。

我正在尝试编写一个程序，允许用户输入 3D 形状，然后输入一些数据来计算其体积。 但是，我不断收到语法错误，箭头指向“elif”的末尾。

我使用https://www.onlinegdb.com/online_python_interpreter作为我的控制台。

# Allows the use of Pi
import math

# Where the user selects the 3D shape
shape = str(input("Enter a Shape you would like to find the volume of! : "))

# Where it takes the user to a shape calculator based on what shape the user inputted
if shape == ("Sphere"):
    def vsphere(r):
        volume = 4.0/3.0*math.pi*r**3
        return volume
# Where the user enters the data of the shape
    radius = float(input("Enter The Volume of Your Sphere! : "))

    print("The Volume of a Sphere with a Radius of ",str(radius)," is ",str(vsphere(radius)))

elif shape == ("Cylinder"):
    def vcylinder(n):
        volume = math.pi * r**2 * h
        return n

r = int(input("Enter the Radius! : "))
h = int(input("Enter the Height! : "))

print("The Volume of a Cylinder with a Radius of ",str(r)," and a Height of ",str(h)," is ",str(vcylinder(math.pi * r**2 * h)))

elif shape == ("Cone"):
    def vcone(n):
        volume = math.pi * r**2 * h * 1/3
        return n

r = int(input("Enter the Radius! : "))
h = int(input("Enter the Height! : "))

print("The Volume of a Cylinder with a Radius of ",str(r)," and a Height of ",str(h)," is ",str(vcone(math.pi * r**2 * h * 1/3)))

elif shape == ("Cube"):
    def vcube(a):
        volume = a**3
        return volume

a = int(input("Enter the Area! : "))

print("The Volume of a Cube with an Area of ",str(a)," is ",str(vcube(a)))

else:
    print("Sorry, that Shape isn't on our List")

    print("Sorry, that Shape isn't on our List")

它应该允许用户输入一个形状（如立方体），将它们带到形状计算器（输入立方体的面积），然后根据输入的数据计算体积。

相反，当我运行程序时，它给了我这个错误消息：

文件“main.py”，第 27 行
elif 形状 ==（“锥体”）：
^
语法错误：无效语法

Answer 1

您遇到了缩进错误问题。

你必须缩进

    r = int(input("Enter the Radius! : "))
    h = int(input("Enter the Height! : "))

如果我们不缩进它们，则视为您已退出if块。 因此，当我们在if之外遇到elif if ，我们会得到一个语法错误。

# Allows the use of Pi
import math

# Where the user selects the 3D shape
shape = str(input("Enter a Shape you would like to find the volume of! : "))

# Where it takes the user to a shape calculator based on what shape the user inputted
if shape == ("Sphere"):
    def vsphere(r):
        volume = 4.0/3.0*math.pi*r**3
        return volume
# Where the user enters the data of the shape
    radius = float(input("Enter The Volume of Your Sphere! : "))

    print("The Volume of a Sphere with a Radius of ",str(radius)," is ",str(vsphere(radius)))

elif shape == ("Cylinder"):
    def vcylinder(n):
        volume = math.pi * r**2 * h
        return n

    r = int(input("Enter the Radius! : "))
    h = int(input("Enter the Height! : "))

    print("The Volume of a Cylinder with a Radius of ",str(r)," and a Height of ",str(h)," is ",str(vcylinder(math.pi * r**2 * h)))

elif shape == ("Cone"):
    def vcone(n):
        volume = math.pi * r**2 * h * 1/3
        return n

    r = int(input("Enter the Radius! : "))
    h = int(input("Enter the Height! : "))

    print("The Volume of a Cylinder with a Radius of ",str(r)," and a Height of ",str(h)," is ",str(vcone(math.pi * r**2 * h * 1/3)))

elif shape == ("Cube"):
    def vcube(a):
        volume = a**3
        return volume

    a = int(input("Enter the Area! : "))

    print("The Volume of a Cube with an Area of ",str(a)," is ",str(vcube(a)))

else:
    print("Sorry, that Shape isn't on our List")

    print("Sorry, that Shape isn't on our List")

Answer 2

你在搞缩进。

您的elif必须处于同一缩进级别

. Cylinder必须是elif shape == ("Cylinder"): 。

elif shape == ("Cylinder"):
    def vcylinder(n):
        volume = math.pi * r**2 * h
        return n
# vvvvvvvvvvvvvvvvvv NEED INDENTATION vvvvvvvvvvvvvvvvvv 
r = int(input("Enter the Radius! : "))
h = int(input("Enter the Height! : "))

print("The Volume of a Cylinder with a Radius of ",str(r)," and a Height of ",str(h)," is ",str(vcylinder(math.pi * r**2 * h)))
# ^^^^^^^^^^^^^^^^^^ NEED INDENTATION ^^^^^^^^^^^^^^^^^^
elif shape == ("Cone"):
    def vcone(n):
        volume = math.pi * r**2 * h * 1/3
        return n

ps：比较2个字符串时不需要使用括号