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Python: Input a number, if it is not a number generates an error message

Python Basic: Exercise-113 with Solution

Write a Python program to input a number, if it is not a number generates an error message.

Sample Solution-1:

Python Code:

while True:
    try:
        a = int(input("Input a number: "))
        break
    except ValueError:
        print("\nThis is not a number. Try again...")
        print()

Sample Output: 

Input a  number: abc                                                                                          
                                                                                                              
This is not a number.  Try again...                                                                           
                                                                                                              
Input a  number: 150

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:


Sample Solution-2:

Python Code:

x = 1.23
x_int = x.is_integer()
print("Check if x is an integer!")
print(x_int)
y= 1.0
y_int = y.is_integer()
print("Check if y is an integer!")
print(y_int)

Sample Output: 

Check if x is an integer!
False
Check if y is an integer!
True

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:


Sample Solution-3:

Python Code:

x = 1.0
x_int = isinstance(x, int)
print("Check if x is an integer!")
print(x_int)
y = 1
y_int = isinstance(y, int)
print("Check if y is an integer!")
print(y_int)

Sample Output: 

Check if x is an integer!
False
Check if y is an integer!
True

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:


Python Code Editor:

 

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Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os
cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

  • The os and os.path modules.
  • The __file__ constant
  • os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
  • os.path.dirname(path) (returns "the directory name of pathname path")
  • os.getcwd() (returns "a string representing the current working directory")
  • os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m