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类的定义与使用

cball = Projectile(angle, vel, h0)中， cball传入给self

一个炮弹从某个倾角射出计算水平位移和大致飞行时间的程序

# projectile.py
from math import radians, sin , cos

##############类的定义#######
class Projectile():

    def __init__(self, angle, velocity, height):
        self.xpos = 0.0
        self.ypos = height
        theta = radians(angle)
        self.xvel = velocity * cos(theta)
        self.yvel = velocity * sin(theta)
        self.totaltime = 0.0

    def update(self, time):
        self.xpos = self.xpos + time * self.xvel
        yvel1 = self.yvel - 9.8 * time
        self.ypos = self.ypos + time * (self.yvel + yvel1) / 2.0
        self.yvel = yvel1
        self.totaltime = self.totaltime + time

    def getX(self):
        return self.xpos

    def getY(self):
        return self.ypos
#############################

###############函数定义########
def getIputs():
    a = float(input("Enter the lanuch angle (in degrees):"))
    v = float(input("Enter the lanuch velocity (in meters/sec):"))
    h = float(input("Enter the lanuch height (in meters):"))
    t = float(input("Enter the internal between position calculations:"))
    return a, v, h, t

def main():
    angle, vel, h0, time = getIputs()
    cball = Projectile(angle, vel, h0)
    while cball.getY() >= 0:
        cball.update(time)
    print("\nDistance traveled: {0:0.1f} meters.".format(cball.getX()))
    print("\nTotal time spent is roughly: {0:0.1f} sceonds.".format(cball.totaltime))
#############################

###########函数调用###########
if __name__ == '__main__':
    main()

运行示例：

'''
Enter the lanuch angle (in degrees):50
Enter the lanuch velocity (in meters/sec):1
Enter the lanuch height (in meters):50
Enter the internal between position calculations:1

Distance traveled: 2.6 meters.

Total time spent is roughly: 4.0 sceonds.

'''