Python 简单的银行系统
以下实例为学习 Python 银行系统的操作：
python
means = [0, 0, 0]
loan = 0
rate = 0
pay = 0
investment = 0
annual_rate = 0
# 计算定投预期收益
# 定投收益的计算公式为：M=a(1+x)[-1+(1+x)^n]/x;
# 其中M代表预期收益，a代表每期定投金额，x代表收益率，而n代表定投期数。
# 假设用户每月定投金额为300元，一年也就是3600元，年收益率为15%，
# 定投期限为35年，则可以计算出收益为3600(1+15%)[-1+(1+15%)^35]/15%=3648044元。
def fixed_investment(inv, a_rate, y):
global means
inv = 12 * inv
a_rate = a_rate / 100
if a_rate == 0:
expected = 0
else:
expected = inv * (1 + a_rate) * (pow((1 + a_rate), y) - 1) / a_rate
print("定投的预期收入为: %.2f" % expected)
means[1] = expected
return expected
def balance():
total = 0
for i in means:
total += i
print("你的资产总额为：%.2f" % total)
print("你的资产明细为：\n")
print("存款：%.2f" % means[0])
print("理财：%.2f" % means[1])
print("负债：%.2f" % means[2])
def saving(amount):
global means
if amount < 0:
print("存款金额不可小于 0！")
else:
means[0] += amount
print("已存款：%.2f 元" % amount)
print("当前余额：%.2f 元" % means[0])
def draw_money(drawing):
global means
if drawing < 0:
print("取款金额不可小于 0！")
elif drawing > means[0]:
print("取款金额不可超过余额！")
else:
means[0] -= drawing
print("已取款： %.2f 元" % drawing)
print("当前余额： %.2f 元" % means[0])
def loans(loan, rate, pay, years):
global means
if pay < (loan - pay) * rate:
print("你是还不完的！！！")
else:
if years == 0:
count = 0
while loan > 0:
loan -= pay
loan *= (1 + rate)
count += 1
print("将在 %d 年后还完贷款。" % count)
else:
for _ in range(years):
loan -= pay
if loan == 0:
break
else:
loan *= (1 + rate)
print("你现在的负债是: %.2f" % loan)
# means[2] = loan
return loan
# 未来财务状况
def future(years):
income = fixed_investment(investment, annual_rate, years)
debt = loans(loan, rate, pay, years)
captial = means[0] + income - debt
print("你第%i年的总资产有: %.3f" % (years, captial))
def init():
print()
print('''以下为可办理的业务：
1. 查询资产
2. 存款
3. 取款
4. 计算复利
5. 计算贷款
6. 计算未来资产
q. 退出''')
def main():
init()
while True:
choice = input("请输入您要办理的业务代码: ")
# 查询余额
if choice == "1":
balance()
# 存款
elif choice == "2":
inc = float(input("请输入存款金额: "))
saving(inc)
# 取款
elif choice == "3":
dec = float(input("请输入取款金额: "))
draw_money(dec)
# 计算定投
elif choice == "4":
investment = float(input("请输入每月定投金额: "))
annual_rate = float(input("请输入年收益率: "))
years = int(input("请输入定投期限(年): "))
if investment <= 0 or annual_rate <= 0 or years <= 0:
print("输入的数据有误")
else:
money = fixed_investment(investment, annual_rate, years)
print("最终收获: %.2f 元" % money)
# 计算贷款
elif choice == "5":
loan = float(input("请输入当前贷款: "))
rate = float(input("请输入年利率: "))
pay = float(input("请输入每年还款: "))
if loan <= 0 or rate <= 0 or pay <= 0:
print("输入的数据有误")
else:
loans(loan, rate, pay, 0)
elif choice == "6":
years = int(input("希望查询多少年后的财务状况? "))
future(years)
# 退出
elif choice == "q":
print("欢迎下次光临！再见！")
break
else:
print("你输入的指令有误，请重新输入\n")
if __name__ == '__main__':
main()