无效的语法，if 语句。如果时间 < 0

【问题标题】：invalid syntax, if statement. if time < 0无效的语法，if 语句。如果时间 < 0
【发布时间】：2018-02-22 02:05:19
【问题描述】：

def main():
    get_variables()

def get_variables():
    initial_position = float(input("Enter the object's initial position: "))

    initial_velocity = float(input("Enter the object's initial velocity: "))

    acceleration = float(input("Enter the object's acceleration: "))

    time = float(input("Enter the time that has passed: "))
    if time < 0
        print('The time cannot be negative')
        time = float(input('Enter a valid time: ')

    #formula
    position_of_object = initial_position + initial_velocity * time + 0.5 * acceleration * time ** 2

    #Display Position of object
    print("The position of the object is: ", position_of_object)



    while keep_going == 'y'
        keep_going = input("Do you want to calculate another Object's poistion?" + \
                       'position_of_object (Enter y for yes): ') 

main()

这是我的作业，上面写着

"如果时间

我对编程几乎一无所知，并且正在参加有关它的在线课程。请告诉我哪里错了

【问题讨论】：

标签： python syntax

【解决方案1】：

您的代码中似乎很少有错误：

1：缺少“:”和“)”：

    if time < 0
        print('The time cannot be negative')
        time = float(input('Enter a valid time: ')

应改为：

    if time < 0:
        print('The time cannot be negative')
        time = float(input('Enter a valid time: '))

2：在 wile 循环中缺少“：”：

    while keep_going == 'y'
        keep_going = input("Do you want to calculate another Object's 
                      poistion?" + \
                      'position_of_object (Enter y for yes): ')

应该改成

    while keep_going == 'y':
              keep_going = input("Do you want to calculate another Object's 
                    poistion?" + \
                   'position_of_object (Enter y for yes): ')

【讨论】：