Question

我是Python的新手。我试着制作一个基本的计算器，但我真的找不到问题。它返回0退出代码，但没有任何内容出现，没有任何输入。任何有关这方面的帮助将非常感激。谢谢。

def add(num1, num2):
    return num1 + num2

def subtract(num1, num2):
    return num1 - num2

def div(num1, num2):
    return num1/num2

def multi(num1,num2):
    return num1*num2

def main():
    operation = input("What do you want to do?(+, -, *, or /):")
    if (operation != "+" and operation != "-" and operation != "*" and operation != "/"):
        print("Your input is invalid. Please enter a valid input.")
    else:
        num1 = float(input("Enter value for num1: "))
        num2 = float(input("Enter value for num2: "))
        if (operation == "+"):
            print(add(num1, num2))
        elif (operation == "-"):
            print(subtract(num1, num2))
        elif (operation == "*"):
            print(multi(num1,num2))
        elif (operation == "/"):
            print(div(num1,num2))

    main()

Answer 1

我想你错过了：

if __name__ == "__main__":
    main()

您对main()内部main的来电本身无法执行，这可能是您无法获得任何意见的原因。

除此之外，您的代码应按预期工作（请确保您不要除以零;）。

编辑：为了让我的回答更加明显，你应该做到：

def main():
    operation = input("What do you want to do?(+, -, *, or /):")
    if (operation != "+" and operation != "-" and operation != "*" and operation != "/"):
        print("Your input is invalid. Please enter a valid input.")
    else:
        num1 = float(input("Enter value for num1: "))
        num2 = float(input("Enter value for num2: "))
        if (operation == "+"):
            print(add(num1, num2))
        elif (operation == "-"):
            print(subtract(num1, num2))
        elif (operation == "*"):
            print(multi(num1,num2))
        elif (operation == "/"):
            print(div(num1,num2))

if __name__ == "__main__":
    main()

Answer 2

根据上面的代码，您实际上永远不会运行main()。现在，您已经说过main的定义是提示用户，检查输入是否正确，然后进行数学运算。最后的main()导致程序在执行完所有操作后重复（不确定是否需要循环）。

如果你不想要循环，只想运行计算器一次，只需删除最后一个main()的缩进，因为现在缩进意味着它在def main()内。只需将其向左移动到与def main():相同的缩进级别，您的程序就可以正常运行。

Answer 3

func loadBy(_ req: Request) throws -> Future<[News]> {
        let parentId = try req.parameters.next(String.self)
        let parent = try self.findParentBy(req, parentId: parentId)
        var childNews: [News] = []

        return parent.flatMap(to: [News].self) { parentNews in
            return parentNews!.childIds.map { (key) in
                return News.query(on: req).filter(\News.newsId == key).first().map(to: Void.self) { child in
                    if let child = child {
                        childNews.append(child)
                    }
                }
            }.flatten(on: req).map {
                return childNews
            }
        }
    }

func loadBy(_ req: Request) throws -> Future<[News]> {
        let parentId = try req.parameters.next(String.self)
        let parent = try self.findParentBy(req, parentId: parentId)
        return parent.flatMap(to: [News].self) { parentNews in
            return News.query(on: req).filter(\News.newsId ~~ parentNews!.childIds).all()
        }
    }

Answer 4

基本计算器：

方法1：

# This function adds two numbers 
def add(x, y):
    return x + y
# This function subtracts two numbers 
def subtract(x, y):
    return x - y
# This function multiplies two numbers
def multiply(x, y):
    return x * y
# This function divides two numbers
def divide(x, y):
    return x / y
print("Select operation.")
print("1.Add")
print("2.Subtract")
print("3.Multiply")
print("4.Divide")
# Take input from the user 
choice = input("Enter choice(1/2/3/4): ")
num1 = float(input("Enter first number (Should be in numeric form): "))
num2 = float(input("Enter second number (Should be in numeric form): "))
if choice == '1':
    print(num1,"+",num2,"=", add(num1,num2))
elif choice == '2':
    print(num1,"-",num2,"=", subtract(num1,num2))
elif choice == '3':
    print(num1,"*",num2,"=", multiply(num1,num2))
elif choice == '4':
    print(num1,"/",num2,"=", divide(num1,num2))
else:
    print("Invalid input")

方法2：

print("Select operation.")
print("1.Add")
print("2.Subtract")
print("3.Multiply")
print("4.Divide")
# Take input from the user 
choice = input("Enter choice(1/2/3/4): ")
num1 = float(input("Enter first number (Should be in numeric form): "))
num2 = float(input("Enter second number (Should be in numeric form): "))
if choice == '1':
    print(num1,"+",num2,"=", num1+num2)
elif choice == '2':
    print(num1,"-",num2,"=", num1-num2)
elif choice == '3':
    print(num1,"*",num2,"=", num1*num2)
elif choice == '4':
    print(num1,"/",num2,"=", num1/num2)
else:
    print("Invalid input")

学习愉快...：）

Answer 5

while True:
 print("PRINT 'E' for exit")
 given_number=input("Give the operation :")
 given_number_in_string=str(given_number)

 position_of_multiplication=(given_number_in_string.find("*"))
 position_of_addition=(given_number_in_string.find("+"))
 position_of_substraction=(given_number_in_string.find("-"))
 position_of_division=(given_number_in_string.find("/"))



 if position_of_multiplication >= 0:

   position_of_multiplication=(given_number_in_string.find("*"))
   first_no=float(given_number_in_string[0:position_of_multiplication])
   second_no=float(given_number_in_string[position_of_multiplication+1:16])
   print(f"answer is  {first_no*second_no}")
   a=input("")

 elif position_of_addition >= 0:

    position_of_addition=(given_number_in_string.find("+"))
    first_no=float(given_number_in_string[0:position_of_addition])
    second_no=float(given_number_in_string[position_of_addition+1:16])
    print(f"answer is  {first_no+second_no}")
    s=input("")

 elif position_of_substraction >= 0:

    position_of_substraction=(given_number_in_string.find("-"))
    first_no=float(given_number_in_string[0:position_of_substraction])
    second_no=float(given_number_in_string[position_of_substraction+1:16])
    print(f"answer is  {first_no-second_no}")
    s=input("")

 elif position_of_division >= 0:

    position_of_division=(given_number_in_string.find("/"))
    first_no=float(given_number_in_string[0:position_of_division])
    second_no=float(given_number_in_string[position_of_division+1:16])
    print(f"answer is  {first_no/second_no}")
    s=input("")


 if given_number_in_string == "E":
    break

Python中的基本计算器

5 个答案: