while循環在Python中持續運行，輸入良好或不好？

嗨，這是我的第一個Python代碼，與我一起裸露。我正在編寫一個代碼，要求用戶輸入一個百分比，並一直詢問，直到用戶輸入可接受的輸入。然而當我運行這個時，無論輸入什麼樣的輸入，while循環都不會中斷。while循環在Python中持續運行，輸入良好或不好？

這裏是我的代碼：

import math 

while True: 
    try: 
     entered = float(raw_input("Please enter the velocity (as a percentage of the speed of light): ")) 
    except ValueError: 
     print("Sorry, an acceptable input was not entered. Try again.") 
     continue 

    if entered > 100: 
     print("Sorry, a velocity greater than the speed of light cannot be used. Try again.") 
     continue 
    elif entered <= 0: 
     print("Sorry, a percent cannot be negative. Try again.") 
     continue 
    else: 
     #the percent entered is valid, break out of while loop 
     break 

print("Ship is traveling at ", entered, "% the speed of light.") 
print(" ") 

speedOfLight = 299792458       #speed of light constant 
percentage = entered/100      #turn entered percent into decimal 
speed = speedOfLight * percentage    #actual speed (in m/s)   
denominator = math.sqrt(1 - (percentage ** 2)) #denominator of factor equation 
factor = 1/denominator      #solve for given factor equation 

shipWeight = 70000 * factor      #given ship weight * factor 
alphaCentauri = 4.3/factor      # given times divided by the factor 
barnardsStar = 6.0/factor 
betelgeuse = 309 /factor 
andromeda = 2000000/factor 

print("At this speed: ") 
print(" Weight of the shuttle is ", shipWeight) 
print(" Perceived time to travel to Alpha Centauri is ", alphaCentauri, " years.") 
print(" Perceived time to travel to Barnard's Star is ", barnardsStar, " years.") 
print(" Perceived time to travel to Betelgeuse is ", betelgeuse, " years.") 
print(" Perceived time to travel to Andromeda Galaxy is ", andromeda, " years.")

來源

2016-03-31 Clarisa

請花時間來修復縮進，使我們可以幫助你的作品如下。 – Dzhao

你壓痕有點靠不住，代碼永遠不會到達break聲明，因爲你在continue之前的循環。幸運的是，你可以使用和else關鍵字，使其工作：

while True: 
    try: 
     entered = float(raw_input("Please enter the velocity (as a percentage of the speed of light): ")) 
    except ValueError: 
     print("Sorry, an acceptable input was not entered. Try again.") 
     continue 
    else: # no exception 
     if entered > 100: 
      print("Sorry, a velocity greater than the speed of light cannot be used. Try again.") 
      continue 
     elif entered <= 0: 
      print("Sorry, a percent cannot be negative. Try again.") 
      continue 
     else: 
      #the percent entered is valid, break out of while loop 
      break

來源

2016-03-31 03:05:54 Ben

是啊我的壞我總是弄亂縮進當我在這個網站上輸入代碼。但是，謝謝你，它像一個魅力工作！ – Clarisa

@Clarisa一旦你習慣了縮進，python就是其中最優秀的語言之一。好好享受：） – Ben

您檢查您的except內部數據的輸入。除非投射到float產生ValueError，否則你將永遠不會進入你的場地。

你只是想移動except塊之外的條件，所以你可以檢查經過float鑄造的數據：

while True: 
    try: 
     entered = float(input("Please enter the velocity (as a percentage of the speed of light): ")) 
    except ValueError: 
     print("Sorry, an acceptable input was not entered. Try again.") 
     continue 

    if entered > 100: 
     print("Sorry, a velocity greater than the speed of light cannot be used. Try again.") 
     continue 
    elif entered <= 0: 
     print("Sorry, a percent cannot be negative. Try again.") 
     continue 
    else: 
     #the percent entered is valid, break out of while loop 
     break

來源

2016-03-31 03:04:38 idjaw

我認爲（希望）編輯搞砸了，因爲它是無效的語法寫在問題 – TinyTheBrontosaurus

你甚至都不需要繼續/休息，以使這項工作。您還需要「導入數學」，一旦最終擺脫while循環，這將很重要。

你需要做的是觀察凹痕。 try/except的位置不正確 - 如果這反映了代碼實際上是如何編寫的，那將會說明你永遠不會停止while循環。

按你們的要求，只有縮進修復和「進口數學」

import math 

valid = False 

while not valid: 
    try: 
      entered = float(raw_input("Please enter the velocity (as a percentage of the speed of light): ")) 
    except ValueError: 
      print("Sorry, an acceptable input was not entered. Try again.") 
      continue 

    if entered > 100: 
     print("Sorry, a velocity greater than the speed of light cannot be used. Try again.") 
    elif entered <= 0: 
     print("Sorry, a percent cannot be negative. Try again.") 
    else: 
     #the percent entered is valid, break out of while loop 
      valid = True 

print("Ship is traveling at ", entered, "% the speed of light.") 
print(" ") 

speedOfLight = 299792458       #speed of light constant 
percentage = entered/100      #turn entered percent into decimal 
speed = speedOfLight * percentage    #actual speed (in m/s)   
denominator = math.sqrt(1 - (percentage ** 2)) #denominator of factor equation 
factor = 1/denominator      #solve for given factor equation 

shipWeight = 70000 * factor      #given ship weight * factor 
alphaCentauri = 4.3/factor      # given times divided by the factor 
barnardsStar = 6.0/factor 
betelgeuse = 309 /factor 
andromeda = 2000000/factor 

print("At this speed: ") 
print(" Weight of the shuttle is ", shipWeight) 
print(" Perceived time to travel to Alpha Centauri is ", alphaCentauri, " years.") 
print(" Perceived time to travel to Barnard's Star is ", barnardsStar, " years.") 
print(" Perceived time to travel to Betelgeuse is ", betelgeuse, " years.") 
print(" Perceived time to travel to Andromeda Galaxy is ", andromeda, " years.")

來源

2016-03-31 03:14:51 Lost

while循環在Python中持續運行，輸入良好或不好？

回答

相關問題