函數返回無

Question

我有以下腳本：

def collectUserPrompt():  

    xml_file = raw_input('Enter the full file path (ex: C:\Users\Stan\Documents\myxml.xml):') 

    try: 
     os.path.isfile(xml_file) 
     print 'good path' 
    except: 
     print "Please enter a valid xml file path!" 
     collectUserPrompt() 

    multiplier_input = raw_input('Enter XML multiplier (numbers only):') 
    try: 
     multiplier = int(multiplier_input) 
     print 'good multiplier' 
    except : 
     print "Please enter a valid integer!" 
     collectUserPrompt() 

     return xml_file, multiplier 

user_input = collectUserPrompt() 
print user_input 

當我跑，我得到：

Enter the full file path (ex: C:\Users\LIDMZ3W\Documents\myxml.xml):C:\Users\Stan\Documents\Aptana Studio 3 Workspace\ADFTest\src\Training\nascoUMBY.xml 
good path 
Enter XML multiplier (numbers only):3 
good multiplier 
None 

它看起來像我每次回國None，當我試圖從raw_input函數返回驗證的用戶輸入。

Answer 1

您的return聲明位於except區塊中。看起來好像你打算直接在函數的塊中。也就是說，你需要在縮進時將它取回一級：

def collectUserPrompt():  

    xml_file = raw_input('Enter the full file path (ex: C:\Users\Stan\Documents\myxml.xml):') 

    try: 
     os.path.isfile(xml_file) 
     print 'good path' 
    except: 
     print "Please enter a valid xml file path!" 
     collectUserPrompt() 

    multiplier_input = raw_input('Enter XML multiplier (numbers only):') 
    try: 
     multiplier = int(multiplier_input) 
     print 'good multiplier' 
    except : 
     print "Please enter a valid integer!" 
     collectUserPrompt() 

    return xml_file, multiplier # here!