def get_nums():
nums = []#获取列表
num = input('请输入数字：').strip()
while num != '':
nums.append(num)#添加数字
num = input('请输入数字：').strip()#继续输入数字
return nums#返回给nums

print(get_nums())#将列表显示出来

nums = get_nums()

print(nums)

def get_len(nums):#求长度
count =0
for i in nums:
count += 1
return count

nums = get_nums()#注意此时一定要左对齐，不然会报错，显示nums没有被定义

print(get_len(nums))

def get_add(nums):#求和
sum = 0
for i in nums:
sum += eval(i)#把字符串i变成数字后才能相加
return sum

nums = get_nums()

print(get_add(nums))

def get_mean(nums):#求平均数
sum = 0
for i in nums:
sum += eval(i)
mean = sum / get_len(nums)
return mean

nums = get_nums()

print(get_mean(nums))

def get_var(nums,mean):#求方差,方差的定义是每个变量与平均数差的平方和除以变量的个数
sum = 0
for i in nums:
sum += (mean-eval(i))**2
var = sum / get_len(nums)
return var

nums = get_nums()

mean = get_mean(nums)

print(get_var(nums,mean))

l1=[1, 2, 3, 4, 5, 6]
def get_median(nums):
nums_sort = sorted(nums)#python内置，对所有的对象进行排序操作
size = get_len(nums)
if size % 2 == 0:
med = (eval(nums_sort[size // 2 -1]) + eval(nums_sort[size // 2])) /2
else:
med = eval(nums_sort[size // 2])
return med

nums = get_nums()

print(get_median(nums))

def run():
nums = get_nums()
l1 = ['长度','和','平均值','方差', '中位数']
while True:
print("欢迎来到数学计算器".center(50,"-"))
print("""
1、长度
2、求和
3、求平均值
4、求方差
5、求中位数
6、退出程序
""")
choice = input("请输入您的需求").strip()
result = 0
if choice == "1":
result = get_len(nums)
elif choice == "2":
result = get_add(nums)
elif choice == "3":
result = get_mean(nums)
elif choice == "4":
result = get_var(nums,get_mean(nums))
elif choice == "5":
result = get_median(nums)
elif choice == "6":
print('退出程序')
return
else:
print('输入格式有误')
print(f"{l1[eval(choice) - 1]}:{result}")
run()