Question

Intro to Programming and Logic: Python 2, Chapter 8 – Strings

(so far have learned the way of a program, variables, expressions, statements, functions, interface design, conditional, recursion and iteration)

Write a program that takes a string as a parameter. It will analyze the string and return True if it is a valid float number. It will return False if it is not a valid float value.

Your function should return True in any of these cases: 0.17, .17, 5.27, 6, 7

It should return False in any of these cases: aX, a.4, 4*5, 45.123.345

Write a program that will test this function. It will ask the user for a float. It will then feed that input into the function that was written for this program. It will then print out an appropriate message.

You should have 2 functions – one function called isfloat() and the other is main().

Grading:

Program compiles with no syntax errors: 12 points

Program does what it is supposed to do: 5 points

BONUS: make it also return True for negative floats: 2 points

You have meaningful comments: 3 points

-multi-line comments at top to describe what the program does

-comments that describe what your functions do -comments in your program wherever else would be useful to the reader of your code

Answer 1

Hello, here is the completed code you wanted. Every important statement is explained using comments. Please check and let me know if you have any doubts. Thanks.

I have also attached screen shot of the code also. If any compilation error related to Code indentation occurs please compare and correct the code with screen shot.

CODE

#isfloat function
def isfloat(string):
   """
    The function to analyze the string whether
   it is a valid float value or not
  
    Arguments:
    string = input string from user
  
    Returns:
    True = if input string is a valid float value
   False = if input string is not a valid float value
    """
   #try block
   try:
       #try converting input string into float
       #if string converts into float
       #return True
       float(string)
       return True
   #except block
   except ValueError:
       #if string is not a valid float
       #if it can't convert into float which will raise a ValueError
       #returns False
       return False

#main function
def main():
   """
   The function to test isfloat function
  
   Called Functions:
   isfloat() = analyze the string whether
   it is a valid float value or not.
  
   Variables:
   string = to input string from user
   """
   #prompt for float value as string
   string = raw_input("Enter a float value: ")
  
   #if isfloat returns True
   if isfloat(string):
       #prints message
       print(string+" is a valid float")
   #if isfloat returns False
   else:
       #prints message
       print(string+" is not a valid float")

#calling main function
if __name__ == "__main__":
   main()
      

OUTPUT

CODE SCREEN SHOT