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以下是我在 Python 2.7 中构建的一个简单的密耳到度数转换计算器的（半）成品版本，作为学习练习。我是 Python 新手，仍在解决问题。前提是，用户选择将密耳转换为度数，反之亦然。用户输入所选单位的方位角并将其转换为另一个。如果用户选择了无效的菜单选项，他会收到这样的通知。如果他进入范围之外的方位角（度数为 1-360，密耳为 1-6400），他会收到通知并且必须重新开始。问题是如果用户输入了一个无效的方位角，比如 365 度，他会被踢回菜单。有没有办法返回到 if/else 循环中的上一步？我搜索了论坛和文档，但似乎不可能。另外，由于我是 Python 新手，如何使这段代码更高效？我是否需要在函数定义中包含if和elif语句，或者我可以将它们组合起来而不会产生错误或冗余输出？我这样做并不成功。欢迎和赞赏所有意见。

#Mil-Deg.py
#Simple Mils / Degrees Conversion Calculator
#6 JAN 2013

#Note: 6400 mils / 360 degrees in a circle. 17.78 mils to one degree.

import sys
import math
import winsound

#Define menu function
def menu():                     

    print 
    print " Mils / Degrees Conversion Calculator"
    print "-" * 38
    print 
    print "Options: "
    print "1. Degrees to Mils"
    print 
    print "2. Mils to Degrees"
    print 
    print "3. Quit"
    print "-" * 20
    print 
    return input ("Choose your option: ")
    print 

#Define mils to degrees function    
def m2d(a):
    if a <= 6400 and a >= 1:    #get user input within given range      
        b = 17.78
        c = round((a / b),0)    #convert and round to nearest degree  
        if c > 359 or c < 1:    #change 0 degrees to 360               
            c = 360
            #Output
            print
            print a, "mils =", int (c), "degrees"    
        else:
            print
            print a, "mils =", int (c), "degrees"
    elif a > -1 and a < 1:      #change 0 mils to 6400
        a = 6400
        b = 17.78
        c = round((a / b), 0)   #math, same as above
        if c > 359 or c < 1:    #0 to 360, same as above              
            c = 360
            #Output
            print
            print 6400, "mils =", int (c), "degrees"   
        else:
            print
            print a, "mils =", int (c), "degrees"
    else:
        #warning, mulligan
        winsound.Beep(440, 500)
        print 
        print "*** There are only 6400 mils in a circle. Try again. ***"
    print
    print "-" * 38
    print

#define degrees to mils function        
def d2m(b):
    if b <= 360 and b > 0:          #get user input within given range
        a = 17.78
        c = round((b * a),0)        #convert and round to nearest mil
        if c >= 6400:               #set limit to 6400 mils
            c = 6400
            #Output
            print
            print b, "degrees =", int (c), "mils"
        else:
            print
            print b, "degrees =", int (c), "mils"
    elif b > -1 and b < 1:          #change 0 to 360 degrees
        b = 360
        a = 17.78
        c = round((b * a),0)        #math, same as above
        if c >= 6400:
            c = 6400
            #Output
            print
            print 360, "degrees =", int (c), "mils"
        else:
            print
            print b, "degrees =", int (c), "mils"
    else:
        #warning
        winsound.Beep(440, 500)
        print 
        print "*** There are only 360 degrees in a circle. Try again. ***"
    print
    print "-" * 38
    print


#Begin program
loop = 1
choice = 0
while loop == 1:
    choice = menu()                 #Menu function call
    if choice == 1:                 #If user chooses degrees to mils:
        #Output
        print
        print "Enter your azimuth in degrees (1 - 360)"
        print 
        d2m(input("Degrees: "))     #function call

    elif choice == 2:               #If user chooses mils to degrees:
        #Output
        print
        print "Enter your azimuth in mils (1 - 6400)"
        print 
        m2d(input("Mils: "))        #function call

    elif choice == 3:               #If user chooses quit, exit program
        loop = 0

    elif choice != 1 and choice != 2 and choice != 3:   #if user makes invalid menu choice:
        #warning
        winsound.Beep(440, 500)
        print
        print
        print
        print choice, "is not a valid choice."
        print
        print "Please choose from the available options."
        print
        print

print 
print "-" * 38
print 
print "Thank you for using Mil-Deg.py"
print
print
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2 回答 2

0

正如 Ashwini 在评论中提到的那样，您的if-else条件块实际上并不是一个循环，因此使用 while 循环应该回答您问题的程序流程部分。

就 elif 和一般优雅而言，考虑这种使用函数字典处理多个选项的方法；在这里你的少数选项当然没有必要，但它可能会给你一些关于 Python 如何将字典和函数作为类处理的练习。

从风格上讲，我建议使用换行符转义序列\n，而不是所有这些无关的打印语句。

于 2013-01-09T06:03:49.543 回答
0

我稍微清理了您的代码并进行了以下更改：

  1. 修复了您的打印报表
  2. 修复了您的方法名称。方法名称应该是描述性的。字符可以自由输入，所以不要吝啬输入完整的单词。
  3. 你的方法是打印输出和复制逻辑，所以我清理它们只返回值。这样，您以后可以在其他程序中使用这些方法。
  4. 添加了一个辅助方法来检查用户的输入（再次停止重复/复制粘贴相同的代码）。
  5. 我使用format字符串的功能来轻松打印计算。

结果如下：

import sys
import math
import winsound

#Define menu function
def menu():                     
    '''This function prints the main menu''' # this is a docstring for your method
    print "\nMils / Degrees Conversion Calculator"
    print "-" * 38
    print "\nOptions: "
    print "1. Degrees to Mils\n"
    print "2. Mils to Degrees\n"
    print "3. Quit\n"
    print "-" * 20
    print "\n"


#Define mils to degrees function    
def mils_to_degrees(a): # use method names that make sense
    '''This function takes mils and converts them into degrees'''
    b = 17.78
    c = round((a / b),0)    #convert and round to nearest degree  
    if c > 359 or c < 1:    #change 0 degrees to 360               
        c = 360
    return (a,int(c))

#define degrees to mils function        
def degrees_to_mils(b):
    '''This method converts degrees to mils'''
    a = 17.78
    if b == 0:
        b = 360
    c = round((b * a),0)        #math, same as above
    if c > 6400:               #set limit to 6400 mils
        c = 6400
    return (b,c)

def check_input(user_input):
    '''Checks if the input is a number'''
    try:
        converted_number = int(user_input)
    except ValueError:
        return -1
    return converted_number

#Begin program
loop = True
while loop:
    menu()
    choice = int(raw_input("Choose your option: "))
    if choice not in [1,2,3]:
        winsound.Beep(440, 500)
        print choice, "is not a valid choice.\n"
        print "Please choose from the available options.\n"
        menu()
        choice = int(raw_input('Choose your option: '))

    if choice == 1:
        print "\nEnter your azimuth in degrees (0 - 360)\n"
        degrees = check_input(raw_input('Degrees: '))
        if degrees > 360 or degrees < 0:
            print 'Please enter a value between 0 and 360'
        else:
            result = degrees_to_mils(degrees) # function call
            print '{} degrees = {} mils'.format(*result)
            print "-" * 38

    elif choice == 2:               #If user chooses mils to degrees:
        print "\nEnter your azimuth in mils (1 - 6400)\n"
        mils = check_input(raw_input('Mils: '))
        if mils > 6400 or mils < 1:
            print 'Please enter a value between 1 and 6400'
        else:
            result = mils_to_degrees(mils)        #function call
            print '{} mils = {} degrees'.format(*result)
            print "-" * 38

    elif choice == 3: 
        loop = False

print "\n"
print "-" * 38
print "\nThank you for using Mil-Deg.py\n\n"
于 2013-01-10T06:19:09.850 回答