Python LAB 2.8.1.4 Reading ints safely

 Reading ints safely

Reading ints safely

Objectives

• improving the student's skills in defining functions;
• using exceptions in order to provide a safe input environment.

Scenario

Your task is to write a function able to input integer values and to check if they are within a specified range.

LAB Sandbox

The function should:

accept three arguments: a prompt, a low acceptable limit, and a high acceptable limit;

if the user enters a string that is not an integer value, the function should emit the message Error: wrong input, and ask the user to input the value again;

if the user enters a number which falls outside the specified range, the function should emit the message Error: the value is not within permitted range (min..max) and ask the user to input the value again;

if the input value is valid, return it as a result.

Test data

Test your code carefully.

This is how the function should react to the user's input:

Enter a number from -10 to 10: 100

Error: the value is not within permitted range (-10..10)

Enter a number from -10 to 10: asd

Error: wrong input

Enter number from -10 to 10: 1

The number is: 1

Solution:

def read_int(prompt, min, max):

    ok = False
    while not ok:     #---> True
        try:    
            value = int(input(prompt))
            ok = True
        except ValueError:
            print("Error: Wrong Input")
        if ok:
            ok = value >= min and value <= max
        if not ok:
            print("Error: The value is not within range(" + str(min) + ".." + str(max) + ")")
    return value
v = read_int("Enter a number from -10 to 10: ", -10, 10)
print("The number is:", v)