Question

I tried flushing stdout with sys.stdout.flush() but it’s still not working. It works fine until the user only enters C or F which breaks the code. Suffix is the first function called
so I make sure that if the user only enters one character then an error is returned. But once the error is returned the user is no longer able to type ‘quit’ or ‘q’.

#!/usr/local/bin/python
#Converts between Celsius and Fahrenheit
import random, sys

def check_version():
    """
    Make sure user is using Python 3k
    """
    if(sys.version_info[0] != 3):
        print("Stop peddling with your feet Fred!")
        print("Only Py3k supported")
        sys.exit()
    else:
        pass

def random_insult():
    """
    Returns a list of random insults with the sole purpose of insulting the user
    """
    insults = ["Kel", "stimpy", "knucklehead"]
    return insults[random.randrange(3)]

def suffix(temp):
    """
    Accepts the input temperature value which should be a string suffixed by C(c) or F(f)
    Returns the last element of the input string(C or F)
    """
    if(len(temp) >= 2):
        return temp[len(temp)-1]
    else:
        temperature("Input String TOO Small")

def temp_value(temp):
     """
     Accepts the input temperature value which should be a string suffixed by C(c) or F(f)
     Returns the actual temperature value
     """
     if(len(temp) >= 2):
         return temp[0:len(temp)-1]
     else:
         temperature("Input String TOO Small")

def cel_to_far(temp):
    """
    Accepts the input temperature value as Celsius and returns it in Fahrenheit
    """
    try:
        return ((temp * (9/5.0)) + 32)
    except TypeError:
        return "Has to be a number"

def far_to_cel(temp):
    """
    Accepts the input temperature value as Fahrenheit and returns it in Celsius
    """
    try:
        return ((temp - 32) * (5/9.0))
    except TypeError:
        return "Has to be a number"

def temperature(error=None):
    """
    Loops until the user enters quit or q. Allows the user to enter the temperature suffixed by either C(c) or F(f). 
    If suffixed with C then the temperature is taken as Celsius and converted to Fahrenheit.
    If suffixed with F then the temperature is taken as Fahrenheit and converted to Celsius.
    If the user enters anything else be sure to belittle him/her.
    """
    prompt1 = "Enter value suffixed by C or F *\n"
    prompt2 = "Type 'quit' or 'q' to quit     *\n"
    error1 = "What in the world are you doing "+ random_insult() + "?\n"
    error2 = "Did you forget to add C or F to the end of the value?\n"
    example = "Here's an example of input: 30F\n"
    stars = ("*" * 32) + "\n"
    temp = None
    if(error != None):
        print(error)
        print(example)
        temperature()        
    else:
        while(True):
            sys.stdout.flush()
            try:
                temp = input("\n"+ stars + prompt1 + prompt2 + stars + ">>") 
                if( (temp == 'quit') or (temp == 'q')):
                    return

                elif( (suffix(temp) == 'C') or (suffix(temp) == 'c') ):
                    print("Celsius:", temp_value(temp))
                    print("Fahrenheit: {0:.1f}".format(cel_to_far(float(temp_value(temp)))))

                elif( (suffix(temp) == 'F') or (suffix(temp) == 'f') ):
                    print("Fahrenheit:", temp_value(temp))
                    print("Celsius: {0:.1f}".format(far_to_cel(float(temp_value(temp)))))

                else:
                    print(error1 + error2 + example)

            except:
               print("Something went wrong and I don't care to fix it.\n")
               return

if(__name__  == '__main__'):
    check_version()
    temperature()

Answer 1

The problem is that temperature is being called recursively in different places when an error happens and to exit from the program the user has to enter q/quit as many times as temperature was called.

To fix the problem, I suggest to remove all recursive calls and handle the errors in a different way. For example, temp might be checked to make sure it’s a correct input from user and if that’s not the case, print the error message and continue the infinite while loop untill is break is called when the input is either q or quit.