返回循環到特定的多個嘗試/除外子句

Question

我希望用戶爲程序提供輸入，以便如果用戶給出錯誤的輸入，代碼應該提示他們輸入正確的值。

我試過這段代碼，但由於continue聲明它從一開始就運行循環。我希望代碼返回到它各自的try塊。請幫忙。

def boiler(): 
    while True: 

     try: 
      capacity =float(input("Capacity of Boiler:")) 
     except: 
      print ("Enter correct value!!") 
      continue 
     try: 
      steam_temp =float(input("Operating Steam Temperature:")) 
     except: 
      print ("Enter correct value!!") 
      continue 
     try: 
      steam_pre =float(input("Operating Steam Pressure:")) 
     except: 
      print ("Enter correct value!!") 
      continue 
     try: 
      enthalpy =float(input("Enthalpy:")) 
     except: 
      print ("Enter correct value!!") 
      continue 
     else: 
      break 
boiler() 

Answer 1

這是做你想做的嗎？

def query_user_for_setting(query_message): 
    while True: 
     try: 
      return float(input(query_message)) 
     except ValueError: 
      print('Please enter a valid floating value') 


def boiler(): 
    capacity = query_user_for_setting('Capacity of Boiler: ') 
    steam_temp = query_user_for_setting('Operating Steam Temperature: ') 
    steam_pre = query_user_for_setting('Operating Steam Pressure: ') 
    enthalpy = query_user_for_setting('Enthalpy: ') 

    print('Configured boiler with capacity {}, steam temp {}, steam pressure {} and enthalpy {}'.format(
     capacity, steam_temp, steam_pre, enthalpy)) 


if __name__ == '__main__': 
    boiler() 

示例執行

Capacity of Boiler: foo 
Please enter a valid floating value 
Capacity of Boiler: bar 
Please enter a valid floating value 
Capacity of Boiler: 100.25 
Operating Steam Temperature: baz 
Please enter a valid floating value 
Operating Steam Temperature: 200 
Operating Steam Pressure: 350.6 
Enthalpy: foo 
Please enter a valid floating value 
Enthalpy: 25.5 
Configured boiler with capacity 100.25, steam temp 200.0, steam pressure 350.6 and enthalpy 25.5