当我将raw_input（）作为参数时，为什么此功能不起作用？

问题描述

所以我有这个简短的程序，应该给出形状的区域。 当我给它赋值给which_area(x)时，它可以正常工作。 但是，当我将raw_input()作为参数时，（并且因为我将print choose_area放在了底部），shell在输入后回复None 。

我不太确定出了什么问题，但是我认为这与return语句以及我的表达方式有关。

任何帮助表示赞赏：）请，谢谢。

从一开始的程序员。

def triangle_area():
    print "What is the base length?"
    base = raw_input()
    print "What is the height?"
    height = raw_input()
    area = 0.5*float(base)*float(height)
    print "The area of you triangle is:", area

def circle_area():
    print "What is the radius of the circle?"
    radius = raw_input()
    area = 3.14159*(float(radius)**2)
    print "The area of your circle is:", area

def square_area():
    print "What is the length of the side of the square?"
    print "(Remember that squares have equal sides, and if"
    print "you want to enter a seperate length and width"
    print "you have a rectangle.)"
    length = raw_input()
    area = float(length)**2
    print "The area of your square is", area

def which_area(x):
    if x == 1:
        return triangle_area()
    elif x == 2:
        return circle_area()
    elif x == 3:
        return square_area()
    else:
        return "You didn't pick 1, 2, or 3."

def choose_area():
    print "Calculate the area of which shape?"
    print "1. a triangle"
    print "2. a circle"
    print "3. a square"
    print "Enter a number to choose:"
    which_area(raw_input())

print choose_area()

更改您的代码

which_area(raw_input())

至

which_area(int(raw_input()))

可能有几个原因取决于您使用的python版本。

1. 如果使用的是python版本3或更高版本，则由于python版本错误而导致。 它应该变成

    which_area(int(input())) 

或者，如果您将波纹管版本用于python 3.x，则应为（例如-2.7）

   which_area(int(raw_input()))

无论如何，请确保使用强制转换，因为您正在使用输入来输入数字，但是

   raw_input() or input()

函数将输入作为字符串

因此，根据您的计算，如果要获取小数，请使用“ Float”，如果要获取数字，请使用“ int”作为强制转换。

结合以前的答案：

which_area需要一个整数， raw_input()返回一个字符串。 你需要：

    which_area(int(raw_input()))

但是，连同此triangle_area ， circle_area和square_area均不返回任何内容-而是打印一条消息。 您可能想以以下形式结束这些功能：

    return "The area of your triangle is: " + str(area)

（请注意，我在这里仅使用了简单的字符串连接-您可以改用旧样式或新样式的字符串格式）

函数triangle_area，square_area和circle_area没有返回任何值

def triangle_area():
    print "What is the base length?"
    base = raw_input()
    print "What is the height?"
    height = raw_input()
    area = 0.5*float(base)*float(height)
    print "The area of you triangle is:", area
    return area

def circle_area():
    print "What is the radius of the circle?"
    radius = raw_input()
    area = 3.14159*(float(radius)**2)
    print "The area of your circle is:", area
    return area

def square_area():
    print "What is the length of the side of the square?"
    print "(Remember that squares have equal sides, and if"
    print "you want to enter a seperate length and width"
    print "you have a rectangle.)"
    length = raw_input()
    area = float(length)**2
    print "The area of your square is", area
    return area

def which_area(x):
    if x == 1:
        return triangle_area()
    elif x == 2:
        return circle_area()
    elif x == 3:
        return square_area()
    else:
        return "You didn't pick 1, 2, or 3."

def choose_area():
    print "Calculate the area of which shape?"
    print "1. a triangle"
    print "2. a circle"
    print "3. a square"
    print "Enter a number to choose:"
    which_area(int(raw_input()))

print choose_area()

注意：raw_input以promt作为参数，因此您可以执行raw_input（“ Height：”）之类的操作