有条件执行多重比较不起作用

Question

我一直遇到这个python代码的问题.我刚刚开始编码,我无法弄清楚它为什么不起作用.我不能让循环停止重复.无论我输入什么,它都会启动add_item功能.有小费吗？

supply = { #Creates blank dictionary
}
print "Would you like to add anything to the list?"

def add_item(*args):     #Adds a item to the supply dictionary
    print "What would you like to add?"
    first_item = raw_input()
    print "How much does it cost?"
    first_price = raw_input()
    supply[first_item] = float(first_price)

response = raw_input()

while response == "yes" or "Yes" or "YES":
    if response == "yes" or "Yes" or "YES": #Added this because it wasn't working, didn't help
        add_item()
        print "Alright, your stock now reads:", supply
        print "Would you like to add anything else?"
        response = raw_input()
    elif response == "no" or "No" or "NO":
        print "Alright. Your stock includes:" 
        print supply
        break
    else:
        print "Sorry I didn't understand that. Your stock includes:" 
        print supply
        break

print "Press Enter to close"
end_program = raw_input()

Answer 1

你似乎对如何or运作感到困惑.

您的原始表达式可以像这样重写:

(response == "yes") or ("Yes") or ("YES")

也就是说,它测量了三个表达式的真实性:等式表达式,以及剩下的两个字符串表达式中的每一个.双方"Yes"并"YES"evaulate为真,所以你(更多或更少)有:

while (response == "yes") or True or True:

由于"Yes"始终计算为true,因此while表达式始终为true.

尝试:

while response in ( "yes" , "Yes" , "YES"):

或者,更好的是:

while response.lower() == "yes":