Python Exercises: Calculate the sum of two numbers given as strings

Last update on June 12 2025 12:43:13 (UTC/GMT +8 hours)

Add numbers given as strings.

Write a Python program to calculate the sum of two numbers given as strings. Return the result in the same string representation.

Sample Data:
( “234242342341”, “2432342342”) -> “236674684683”
( “”, “2432342342”) -> False ( “1000”, “0”) -> “1000”
( “1000”, “10”) -> “1010”

Sample Solution-1:

Python Code:

# Define a function to add two numbers represented as strings
def test(x, y):
    # Check if either x or y is an empty string, return False if true
    if (x == "" or y == ""):
        return False
    
    # Determine the maximum length between x and y
    m = max(len(x), len(y))
    c = 0  # Initialize carry to 0
    result = ''  # Initialize the result string
    
    # Iterate through the digits of x and y from right to left
    for x, y in zip(x.rjust(m, '0')[::-1], y.rjust(m, '0')[::-1]):
        # Add the digits and the carry
        s = int(x) + int(y) + c
        # Update the carry for the next iteration
        c = 1 if s > 9 else 0
        # Append the last digit of the sum to the result
        result += str(s)[-1]  
    
    # Add the final carry to the result if it is 1
    result = result + str(c) if c == 1 else result
    # Reverse the result and return
    return result[::-1]

# Initialize two string numbers
n1 ="234242342341"
n2 ="2432342342"

# Print the original string numbers
print("Original string numbers:", n1, n2)

# Print a message indicating the addition of the two numbers
print("Check if said two strings represent numbers and add them:")
# Call the function to add the numbers and print the result
print(test(n1, n2))

# Repeat the process with different sets of string numbers
n1 =""
n2 ="2432342342"
print("\nOriginal string numbers:", n1, n2)
print("Check if said two strings represent numbers and add them:")
print(test(n1, n2))

n1 ="1000"
n2 ="0"
print("\nOriginal string numbers:", n1, n2)
print("Check if said two strings represent numbers and add them:")
print(test(n1, n2))

n1 ="1000"
n2 ="10"
print("\nOriginal string numbers:", n1, n2)
print("Check if said two strings represent numbers and add them:")
print(test(n1, n2))

Sample Output:

Original string numbers: 234242342341 2432342342
Check said two strings contain three letters at the same index:
236674684683
Original string numbers:  2432342342
Check said two strings contain three letters at the same index:
False
Original string numbers: 1000 0
Check said two strings contain three letters at the same index:
1000
Original string numbers: 1000 10
Check said two strings contain three letters at the same index:
1010

Flowchart:

Flowchart: Calculate the sum of two numbers given as strings.

Sample Solution-2:

Python Code:

# Define a function to add two numbers represented as strings
def test(x, y):
    # Check if either x or y is an empty string, return False if true
    if (x == "" or y == ""):
        return False
    
    # Convert the string representations of numbers to integers, add them, and convert back to string
    return str(int(x) + int(y))

# Initialize two string numbers
n1 ="234242342341"
n2 ="2432342342"

# Print the original string numbers
print("Original string numbers:", n1, n2)

# Print a message indicating the addition of the two numbers
print("Calculate the sum of two said numbers given as strings:")
# Call the function to add the numbers and print the result
print(test(n1, n2))

# Repeat the process with different sets of string numbers
n1 =""
n2 ="2432342342"
print("\nOriginal string numbers:", n1, n2)
print("Calculate the sum of two said numbers given as strings:")
print(test(n1, n2))

n1 ="1000"
n2 ="0"
print("\nOriginal string numbers:", n1, n2)
print("Calculate the sum of two said numbers given as strings:")
print(test(n1, n2))

n1 ="1000"
n2 ="10"
print("\nOriginal string numbers:", n1, n2)
print("Calculate the sum of two said numbers given as strings:")
print(test(n1, n2))

Sample Output:

Original string numbers: 234242342341 2432342342
Calculate the sum of two said numbers given as strings:
236674684683
Original string numbers:  2432342342
Calculate the sum of two said numbers given as strings:
False
Original string numbers: 1000 0
Calculate the sum of two said numbers given as strings:
1000
Original string numbers: 1000 10
Calculate the sum of two said numbers given as strings:
1010

Flowchart:

Flowchart: Calculate the sum of two numbers given as strings.

For more Practice: Solve these Related Problems:

Write a Python program to add two numbers provided as strings and return the result as a string without converting to integers using iterative digit addition.
Write a Python program to convert two numeric strings to integers, sum them, and convert the result back to a string.
Write a Python program to implement error checking when adding two strings as numbers, returning a specific message if conversion fails.
Write a Python program to use recursion to add two numbers given as strings digit by digit and return the sum as a string.

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