While循环不会停止循环
While循环不会停止循环
提问于 2020-01-15 03:42:04
一般来说，我对python或编码比较陌生，在我的while循环中遇到了一个问题。我想指出的是，while循环只有在变量"loop“= True时才有效
loop = True #Makes the asking sequence work
def loop_again(): #Makes the program ask if you want to continue
loop_again = str(input("Do you want to do this again? Yes or No: "))
if loop_again == "Yes":
loop = True
elif loop_again == "No":
loop = False
else:
print("Please answer yes or no: ")
loop_again当我写"No“时，当程序询问我是否要再次这样做时，它仍然循环序列，即使当我输入"No”时变量" loop“应该为false，这应该会停止循环。
完整代码(代码底部的while循环)：
#Solving for the area in a shape automatically
import math
loop = True #Makes the asking sequence work
def loop_again(): #Makes the program ask if you want to continue
loop_again = str(input("Do you want to do this again? Yes or No: "))
if loop_again == "Yes":
loop = True
elif loop_again == "No":
loop = False
else:
print("Please answer yes or no: ")
loop_again
def sqr_area(): #Asking sequence for the area of the square
if choose == "Square":
a = float(input("Input the length of the side here: "))
print(a ** 2)
loop_again()
def rec_area(): #Asking sequence for the area of the rectangle
if choose == "Rectangle":
a = float(input("Input the length of the long sides here: "))
b = float(input("Input the length of the short sides here: "))
print(a * b)
loop_again()
def tri_area(): #Asking sequence for the area of the triangle
a = float(input("Input the length of the side: "))
b = float(input("Input the length of the height: "))
print((a * b) / 2)
loop_again()
def cir_area(): #Asking sequence for the area of the circle
r = float(input("Length of the radius: "))
print((r ** 2) * math.pi)
loop_again()
while loop == True: #While loop, asking sequence
choose = str(input("Input what shape that you want to figure out the area of here: "))
if choose == "Square":
sqr_area()
elif choose == "Rectangle":
rec_area()
elif choose == "Triangle":
tri_area()
elif choose == "Circle":
cir_area()
else:
print("Invalid shape, Input one of these shapes: Square, Rectangle, Triangle, Circle")
choose提前感谢！
回答 3
Stack Overflow用户
发布于 2020-01-15 03:53:15
不要在应该使用循环的时候使用递归，loop_again应该返回一个值，而不是全局设置loop。
import math
# Returns true once the input is Yes or false once the input is No
def loop_again():
while True:
response = str(input("Do you want to do this again? Yes or No: "))
if response == "Yes":
return True
elif response == "No":
return False
else:
print("Please answer yes or no: ")loop_again应该在相关的*_area函数返回之后调用，而不是在每个函数内部调用。这些函数不需要知道或关心choose的值；只有在需要调用时才会调用它们。
# Print the area of a square
def sqr_area():
a = float(input("Input the length of the side here: "))
print(a ** 2)
# Print the area of a rectangle
def rec_area():
a = float(input("Input the length of the long sides here: "))
b = float(input("Input the length of the short sides here: "))
print(a * b)
# Print the area of a triangle
def tri_area():
a = float(input("Input the length of the side: "))
b = float(input("Input the length of the height: "))
print((a * b) / 2)
# Print the area of a circle
def cir_area():
r = float(input("Length of the radius: "))
print((r ** 2) * math.pi)最后一个循环可以无限运行，直到loop_again返回True。
# Loop until the user chooses to not run again
while True:
choose = input("Input what shape that you want to figure out the area of here: ")
if choose == "Square":
sqr_area()
elif choose == "Rectangle":
rec_area()
elif choose == "Triangle":
tri_area()
elif choose == "Circle":
cir_area()
else:
print("Invalid shape, Input one of these shapes: Square, Rectangle, Triangle, Circle")
continue
if loop_again():
breakStack Overflow用户
发布于 2020-01-15 03:44:10
在loop_again()函数中，您必须在开头添加以下内容：
global loop否则，该变量被视为局部变量，并且不会对外部作用域中的另一个loop变量产生任何影响。
Stack Overflow用户
发布于 2020-01-15 03:49:32
这是一个上下文变量问题。loop_again()中的loop变量和while循环中的变量是不同的。在python中，函数中的每个变量都是局部变量，除非它是一个参数，或者如果你在主函数和函数内部使用了global variable。
因此，将其设置为全局的，或者在函数中传递并返回它
#Solving for the area in a shape automatically
import math
global loop
loop = True #Makes the asking sequence work
def loop_again(): #Makes the program ask if you want to continue
global loop
loop_again = str(input("Do you want to do this again? Yes or No: "))
if loop_again == "Yes":
loop = True
elif loop_again == "No":
loop = False
else:
print("Please answer yes or no: ")
loop_again
def sqr_area(): #Asking sequence for the area of the square
if choose == "Square":
a = float(input("Input the length of the side here: "))
print(a ** 2)
loop_again()
def rec_area(): #Asking sequence for the area of the rectangle
if choose == "Rectangle":
a = float(input("Input the length of the long sides here: "))
b = float(input("Input the length of the short sides here: "))
print(a * b)
loop_again()
def tri_area(): #Asking sequence for the area of the triangle
a = float(input("Input the length of the side: "))
b = float(input("Input the length of the height: "))
print((a * b) / 2)
loop_again()
def cir_area(): #Asking sequence for the area of the circle
r = float(input("Length of the radius: "))
print((r ** 2) * math.pi)
loop_again()
while loop == True: #While loop, asking sequence
global loop
choose = str(input("Input what shape that you want to figure out the area of here: "))
if choose == "Square":
sqr_area()
elif choose == "Rectangle":
rec_area()
elif choose == "Triangle":
tri_area()
elif choose == "Circle":
cir_area()
else:
print("Invalid shape, Input one of these shapes: Square, Rectangle, Triangle, Circle")
choose您需要在每个函数中说明该循环是全局循环，否则python会将其解释为局部变量。
另一种方式是：
import math
loop = True #Makes the asking sequence work
def loop_again(loop ): #Makes the program ask if you want to continue
loop_again = str(input("Do you want to do this again? Yes or No: "))
if loop_again == "Yes":
loop = True
elif loop_again == "No":
loop = False
else:
print("Please answer yes or no: ")
loop_again
return loop
def sqr_area(loop): #Asking sequence for the area of the square
if choose == "Square":
a = float(input("Input the length of the side here: "))
print(a ** 2)
loop = loop_again()
return loop
def rec_area(loop): #Asking sequence for the area of the rectangle
if choose == "Rectangle":
a = float(input("Input the length of the long sides here: "))
b = float(input("Input the length of the short sides here: "))
print(a * b)
loop = loop_again(loop)
return loop
def tri_area(loop): #Asking sequence for the area of the triangle
a = float(input("Input the length of the side: "))
b = float(input("Input the length of the height: "))
print((a * b) / 2)
loop = loop_again()
def cir_area(loop): #Asking sequence for the area of the circle
r = float(input("Length of the radius: "))
print((r ** 2) * math.pi)
loop = loop_again()
while loop == True: #While loop, asking sequence
choose = str(input("Input what shape that you want to figure out the area of here: "))
if choose == "Square":
loop = sqr_area(loop )
elif choose == "Rectangle":
loop = rec_area(loop )
elif choose == "Triangle":
loop = tri_area(loop )
elif choose == "Circle":
loop = cir_area(loop )
else:
print("Invalid shape, Input one of these shapes: Square, Rectangle, Triangle, Circle")
choose```页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/59740698
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