如何在Python中添加变量？

问题描述：

Python noob here。我试图添加一组在'if'语句中定义的输入变量，并且每当我尝试查找总和时，它将只显示内联值。例如，当A，B，c和d等于5，周长= 555 ...如何在Python中添加变量？

shape = raw_input("Is the plot a (q) quadrilateral or (t) triangle?") 
if shape.lower() == "q": 
    a = raw_input("What is the length in feet of side 'a'?") 
    b = raw_input("What is the length in feet of side 'b'?") 
    c = raw_input("What is the length in feet of side 'c'?") 
    d = raw_input("What is the length in feet of side 'd'?") 
elif shape.lower() == "t": 
    a = raw_input("What is the length in feet of side 'a'?") 
    b = raw_input("What is the length in feet of side 'b'?") 
    c = raw_input("What is the length in feet of side 'c'?") 
else: 
    print "Please enter 'q' for quadrilateral or 't' for triangle." 

if shape.lower() == "q": 
    perimeter = a + b + c + d 
elif shape.lower() == "t": 
    perimeter = a + b + c 
else: 
    print "Please make sure you enter numbers only." 

print perimeter

http://www.programmingforums.org/thread22164.html – 2013-05-01 06:54:21

你缺少一个用于加法的int（）。 – squiguy 2013-05-01 06:54:50

答

str值可以被添加到彼此很像号码。您使用的+运算符可以正常工作，但会连接字符串的值。的raw_input结果是一个字符串（str），所以这就是为什么你会在15代替综上所述号码，使用int()加入他们之前强迫为数字，看到'555'：

try: 
    a = int(raw_input('gimme a number')) 
except ValueError as e 
    print 'that was not a number, son'

感谢您的解释。虽然我希望自己有更好的方法来清理它，但它确实有帮助。哦，虽然，继承人是一个新手！ – particlepat 2013-05-01 12:49:13

答

变量a,b,c和d，使用input(prompt)而不是。 raw_input返回一个字符串，但input返回作为python文字计算的控制台输入。（截至目前，你是连接字符串的，而不是整数）。

答

确保您raw_input实际上是一个int（）：

shape = raw_input("Is the plot a (q) quadrilateral or (t) triangle?") 
if shape.lower() == "q": 
    try: 
     a = raw_input("What is the length in feet of side 'a'?") 
     b = raw_input("What is the length in feet of side 'b'?") 
     c = raw_input("What is the length in feet of side 'c'?") 
     d = raw_input("What is the length in feet of side 'd'?") 
     perimeter = int(a) + int(b) + int(c) + int(d) 
    except ErrorValue as e 
     print "Please make sure you enter numbers only." 

elif shape.lower() == "t": 
    try: 
     a = raw_input("What is the length in feet of side 'a'?") 
     b = raw_input("What is the length in feet of side 'b'?") 
     c = raw_input("What is the length in feet of side ' 
     perimeter = int(a) + int(b) + int(c) 
    except ErrorValue as e 
     print "Please make sure you enter numbers only." 
else: 
    print "Please enter 'q' for quadrilateral or 't' for triangle."

答

你的代码是不是一个很好的设计。如果你想添加更多的形状，六角形，八角形等等。你实际上可以使用一个字典存储形状映射到边数。您不必为每个形状编写多个if语句。你将不得不做更少的类型检查，你可以使用python builtin函数sum来返回参数。现在继续尝试以下操作：

d = {'q': 4, 't': 3} 

shape = raw_input("Is the plot a (q) quadrilateral or (t) triangle?\n") 

if shape.lower() not in d: 
    print "Please enter 'q' for quadrilateral or 't' for triangle." 

else: 
    sides = [] 

    for i in range(0,d.get(shape.lower())): 
     side = raw_input("What is the length in feet of side " + str(i+1)) 
     try: 
      sides.append(int(side)) 
     except ValueError: 
      print "Integer value only" 

    print sum(sides)

答

我是用字典做的。

sides = {'a':0,'b': 0,'c': 0,'d': 0} 
perimeter = 0 

shape = raw_input("Is the plot a (q) quadrilatral or (t) triangle?: ") 
if shape.lower() == "q": 
    for side, length in sides.iteritems(): 
     sides[side] = input("What is the length (in feet) of side %s?: " % side) 
     perimeter+=int(sides[side]) 

elif shape.lower() == "t": 
    sides.pop("d",None) 
    for side, length in sides.iteritems(): 
     sides[side] = input("What is the length (in feet) of side %s?: " % side) 
     perimeter+=int(sides[side]) 
else: 
    print "Please enter 'q' or 't'." 

print "Perimeter is: %d" % perimeter

我觉得字典会更容易使用。可能会更清洁，而不是重复自己。

如何在Python中添加变量？

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