我正在 tkinter 上使用 if-else 语句编写货币转换器程序。我只针对六种货币编写了它，而且花费的时间太长。
如果我想写数百种货币怎么办？我也使用 if-else 吗？是否有更有效的方法来编程货币转换器而不使用 If-Else 语句？
from tkinter import ttk
from tkinter import *
import tkinter as tk
class CurrencyConverter(tk.Tk):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.title('Currency Converter')
self.geometry('500x300')
self.currencies_list = ['United States Dollar', 'Pound Sterling', 'Euro', 'Pakistani Rupee', 'Swiss Franc',
'Japanese Yen']
self.usd_to_other_list = [1, 0.72, 0.85, 153.50, 0.94, 110.70]
self.ps_to_other_list = [1.38, 1, 1.18, 212.15, 1.3, 153]
self.euro_to_other_list = [1.18, 0.85, 1, 180.55, 1.11, 130.19]
self.pkr_to_other_list = [0.0065, 0.0047, 0.0055, 1, 0.0061, 0.72]
self.sf_to_other_list = [1.06, 0.77, 0.9, 162.79, 1, 117.46]
self.jy_to_other_list = [0.009, 0.0065, 0.0077, 1.39, 0.0085, 1]
self.from_currency = tk.StringVar()
self.to_currency = tk.StringVar()
self.from_entry_variable = tk.IntVar()
self.to_entry_variable = tk.IntVar()
self.from_entry = ttk.Entry(
self,
textvariable=self.from_entry_variable,
width=40
)
self.from_combobox = ttk.Combobox(
self,
textvariable=self.from_currency,
values=tuple(self.currencies_list),
state='readonly'
)
self.from_combobox.set(self.currencies_list[0])
self.to_entry = ttk.Entry(
self,
textvariable=self.to_entry_variable,
width=40,
state='readonly'
)
self.to_combobox = ttk.Combobox(
self,
textvariable=self.to_currency,
values=tuple(self.currencies_list),
state='readonly'
)
self.to_combobox.set(self.currencies_list[4])
self.from_entry.pack()
self.from_combobox.pack()
self.to_entry.pack()
self.to_combobox.pack()
self.from_entry.bind('<KeyPress>', self.currency_converter)
self.from_entry.bind('<KeyRelease>', self.currency_converter)
def currency_converter(self, event):
try:
if self.from_currency.get() == 'United States Dollar':
if self.to_currency.get() == 'United States Dollar':
converted = int(self.from_entry_variable.get()) * self.usd_to_other_list[0]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Pound Sterling':
converted = int(self.from_entry_variable.get()) * self.usd_to_other_list[1]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Euro':
converted = int(self.from_entry_variable.get()) * self.usd_to_other_list[2]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Pakistani Rupee':
converted = int(self.from_entry_variable.get()) * self.usd_to_other_list[3]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Swiss Franc':
converted = int(self.from_entry_variable.get()) * self.usd_to_other_list[4]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Japanese Yen':
converted = int(self.from_entry_variable.get()) * self.usd_to_other_list[5]
self.to_entry_variable.set(value=f'{converted}')
elif self.from_currency.get() == 'Pound Sterling':
if self.to_currency.get() == 'United States Dollar':
converted = int(self.from_entry_variable.get()) * self.ps_to_other_list[0]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Pound Sterling':
converted = int(self.from_entry_variable.get()) * self.ps_to_other_list[1]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Euro':
converted = int(self.from_entry_variable.get()) * self.ps_to_other_list[2]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Pakistani Rupee':
converted = int(self.from_entry_variable.get()) * self.ps_to_other_list[3]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Swiss Franc':
converted = int(self.from_entry_variable.get()) * self.ps_to_other_list[4]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Japanese Yen':
converted = int(self.from_entry_variable.get()) * self.ps_to_other_list[5]
self.to_entry_variable.set(value=f'{converted}')
elif self.from_currency.get() == 'Euro':
if self.to_currency.get() == 'United States Dollar':
converted = int(self.from_entry_variable.get()) * self.euro_to_other_list[0]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Pound Sterling':
converted = int(self.from_entry_variable.get()) * self.euro_to_other_list[1]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Euro':
converted = int(self.from_entry_variable.get()) * self.euro_to_other_list[2]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Pakistani Rupee':
converted = int(self.from_entry_variable.get()) * self.euro_to_other_list[3]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Swiss Franc':
converted = int(self.from_entry_variable.get()) * self.euro_to_other_list[4]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Japanese Yen':
converted = int(self.from_entry_variable.get()) * self.euro_to_other_list[5]
self.to_entry_variable.set(value=f'{converted}')
elif self.from_currency.get() == 'Pakistani Rupee':
if self.to_currency.get() == 'United States Dollar':
converted = int(self.from_entry_variable.get()) * self.pkr_to_other_list[0]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Pound Sterling':
converted = int(self.from_entry_variable.get()) * self.pkr_to_other_list[1]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Euro':
converted = int(self.from_entry_variable.get()) * self.pkr_to_other_list[2]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Pakistani Rupee':
converted = int(self.from_entry_variable.get()) * self.pkr_to_other_list[3]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Swiss Franc':
converted = int(self.from_entry_variable.get()) * self.pkr_to_other_list[4]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Japanese Yen':
converted = int(self.from_entry_variable.get()) * self.pkr_to_other_list[5]
self.to_entry_variable.set(value=f'{converted}')
elif self.from_currency.get() == 'Swiss Franc':
if self.to_currency.get() == 'United States Dollar':
converted = int(self.from_entry_variable.get()) * self.sf_to_other_list[0]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Pound Sterling':
converted = int(self.from_entry_variable.get()) * self.sf_to_other_list[1]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Euro':
converted = int(self.from_entry_variable.get()) * self.sf_to_other_list[2]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Pakistani Rupee':
converted = int(self.from_entry_variable.get()) * self.sf_to_other_list[3]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Swiss Franc':
converted = int(self.from_entry_variable.get()) * self.sf_to_other_list[4]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Japanese Yen':
converted = int(self.from_entry_variable.get()) * self.sf_to_other_list[5]
self.to_entry_variable.set(value=f'{converted}')
elif self.from_currency.get() == 'Japanese Yen':
if self.to_currency.get() == 'United States Dollar':
converted = int(self.from_entry_variable.get()) * self.jy_to_other_list[0]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Pound Sterling':
converted = int(self.from_entry_variable.get()) * self.jy_to_other_list[1]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Euro':
converted = int(self.from_entry_variable.get()) * self.jy_to_other_list[2]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Pakistani Rupee':
converted = int(self.from_entry_variable.get()) * self.jy_to_other_list[3]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Swiss Franc':
converted = int(self.from_entry_variable.get()) * self.jy_to_other_list[4]
self.to_entry_variable.set(value=f'{converted}')
elif self.to_currency.get() == 'Japanese Yen':
converted = int(self.from_entry_variable.get()) * self.jy_to_other_list[5]
self.to_entry_variable.set(value=f'{converted}')
except TclError:
pass
root = CurrencyConverter()
root.mainloop()
答案 0 :(得分：0)
像这样的一些函数（我没有 Python 编译器 - 可能存在小错误）？
currencies_list = ['United States Dollar', 'Pound Sterling', 'Euro', 'Pakistani Rupee', 'Swiss Franc', 'Japanese Yen']
usd_to_other_list = [1, 0.72, 0.85, 153.5, 0.94, 110.7]
def GetParity(ValueToConvert, FromCurrency, ToCurrency):
SourceIndex = currencies_list.Index(FromCurrency)
DestIndex = currencies_list.Index(ToCurrency)
SourceR = usd_to_other_list(SourceIndex)
DestR = usd_to_other_list(DestIndex)
Result = ValueToConvert * DestR / SourceR
Return(Result)
答案 1 :(得分：0)
所以我设法使用字典对货币转换器进行了编程。使用 if-else 的缺点是您会在所有汇率中忙于输入数百个嵌套的 if-else。
首先，我们需要有一种规范货币或基础货币，所有其他货币都与它进行比较 (from_currency -> base_currency -> to_currency)。然后你可以有一个字典将每种货币映射到一个单一的汇率，它的汇率与规范货币的关系（在规范货币本身的情况下，该汇率将为 1.0）。
此答案的解释由@jonrsharpe 完成。
假设我想从 EUR 转换为 AED。
第 1 步：设置基础/规范货币 (base currency: USD)。
第 2 步：将 EUR 转换为 USD。
第 3 步：将 USD 转换为 AED。
from tkinter import ttk
import tkinter as tk
from functools import partial
class CurrencyConverter(tk.Tk):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.title('Currency Converter')
self.geometry('500x300')
# Base currency: USD
self.rates = {
'USD': 1,
'EUR': 0.85,
'AED': 3.67
}
self.currencies_list = ['USD', 'EUR', 'AED']
self.from_currency = tk.StringVar()
self.to_currency = tk.StringVar()
self.from_entry_variable = tk.IntVar()
self.to_entry_variable = tk.IntVar()
self.from_entry = ttk.Entry(
self,
textvariable=self.from_entry_variable,
width=40
)
self.from_combobox = ttk.Combobox(
self,
textvariable=self.from_currency,
values=tuple(self.currencies_list),
state='readonly'
)
self.from_combobox.set('USD')
self.to_entry = ttk.Entry(
self,
textvariable=self.to_entry_variable,
width=40,
state='readonly'
)
self.to_combobox = ttk.Combobox(
self,
textvariable=self.to_currency,
values=tuple(self.currencies_list),
state='readonly'
)
self.to_combobox.set('EUR')
self.button = ttk.Button(
self,
text='Convert',
command=partial(self.currency_converter, self.from_entry_variable, self.from_currency, self.to_currency)
)
self.from_entry.pack()
self.from_combobox.pack()
self.to_entry.pack()
self.to_combobox.pack()
self.button.pack()
所以，这是我的 currency_converter()。我在这里传递 *args 是因为我想采用三个参数 amount、from_currency、to_currency。
def currency_converter(self, *args):
_amount, _from_currency, _to_currency, = args
amount, from_currency, to_currency = _amount.get(), _from_currency.get(), _to_currency.get()
print(f'Amount: {amount}, From: {from_currency}, To: {to_currency}')
if from_currency != 'USD':
# Suppose I want to convert from EUR to AED.
# Convert EUR to USD.
usd = amount / self.rates[from_currency]
# Convert USD to AED.
amount = usd * self.rates[to_currency]
print(amount)
else:
# In the case of the canonical currency itself, that rate will be 1.0
amount = amount * self.rates[to_currency]
print(amount)
root = CurrencyConverter()
root.mainloop()
注意：我只针对三种货币完成了这项工作，我的规范货币是美元。如果您想添加更多货币，只需将它们以美元汇率添加到 self.rates。