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

Last update on June 12 2025 12:43:07 (UTC/GMT +8 hours)

Add two strings as numbers.

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

Sample Solution-1:

Python Code:

# Define a function to add two numbers represented as strings
def test(n1, n2):
    # Add '0' to the beginning of each input string to handle negative numbers
    n1, n2 = '0' + n1, '0' + n2
    
    # Check if both modified strings are numeric
    if (n1.isnumeric() and n2.isnumeric()):
        # If true, convert the strings to integers, add them, and return the result as a string
        return str(int(n1) + int(n2))
    else:
        # If not numeric, return an error message
        return 'Error in input!'

# Test the function with different input strings and print the results
print(test("10", "32"))
print(test("10", "22.6"))
print(test("100", "-200")) 

Sample Output:

42
Error in input!
Error in input!

Flowchart:

Sample Solution-2:

Python Code:

# Define a function to add two numbers represented as strings
def test(n1, n2):
    # Check if n1 is an empty string, replace it with '0' if true
    if n1 == '':
        n1 = '0'
    	
    # Check if n2 is an empty string, replace it with '0' if true
    if n2 == '':
        n2 = '0'
    
    # Check if both modified strings are numeric
    if n1.isdigit() and n2.isdigit():
        # If true, convert the strings to integers, add them, and return the result as a string
        return str(int(n1) + int(n2))
    else:
        # If not numeric, return an error message
        return 'Error in input!'

# Test the function with different input strings and print the results
print(test("23", "43"))
print(test("12", "11.6"))
print(test("200", "-100")) 

Sample Output:

66
Error in input!
Error in input!

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to add two numbers provided as strings, returning their sum as a string.
• Write a Python program to validate input strings to ensure they represent positive integers before summing them.
• Write a Python program to implement string addition without converting the inputs to integers using iterative digit processing.
• Write a Python program to handle edge cases where one or both input strings are empty and output an error message.

Go to:

• Python Data Type String Exercises Home ↩
• Python Exercises Home ↩

Previous Python Exercise: Check whether any word in a given sting contains duplicate characrters or not.
Next Python Exercise: Remove punctuations from a string.

Python Code Editor: