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Python: Add two strings as they are numbers (Positive integer values)

Python String: Exercise-101 with Solution

Write a Python program to add two strings as they are numbers (Positive integer values). Return a message if the numbers are string.

Sample Solution-1:

Python Code:

def test(n1, n2):
    n1, n2 = '0' + n1, '0' + n2
    if (n1.isnumeric() and n2.isnumeric()):
        return str(int(n1) + int(n2))
    else:
        return 'Error in input!'
print(test("10", "32"))
print(test("10", "22.6"))
print(test("100", "-200"))

Sample Output:

42
Error in input!
Error in input!

Flowchart:

Flowchart: Add two strings as they are numbers (Positive integer values).

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:

def test(n1, n2):
  if n1 == '':
    n1= '0'
  if n2 == '':
    n2 = '0'
  if n1.isdigit() and n2.isdigit():
    return str(int(n1)+int(n2))
  return 'Error in input!'
print(test("23", "43"))
print(test("12", "11.6"))
print(test("200", "-100"))

Sample Output:

66
Error in input!
Error in input!

Flowchart:

Flowchart: Add two strings as they are numbers (Positive integer values).

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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Previous: Write a Python program to check whether any word in a given sting contains duplicate characrters or not. Return True or False.
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Python: Tips of the Day

Check if a given key already exists in a dictionary:

In is the intended way to test for the existence of a key in a dict.

d = {"key1": 10, "key2": 23}

if "key1" in d:
    print("this will execute")

if "nonexistent key" in d:
    print("this will not")

If you wanted a default, you can always use dict.get():

d = dict()

for i in range(100):
    key = i % 10
    d[key] = d.get(key, 0) + 1

and if you wanted to always ensure a default value for any key you can either use dict.setdefault() repeatedly or defaultdict from the collections module, like so:

from collections import defaultdict

d = defaultdict(int)

for i in range(100):
    d[i % 10] += 1

but in general, the in keyword is the best way to do it.

Ref: https://bit.ly/2XPMRyz