Python: Alternate the case of each letter in a given string and the first letter must be uppercase

Last update on April 17 2025 13:05:07 (UTC/GMT +8 hours)

Alternate Case of String

Write a Python program that alternates the case of each letter in a given string, with the first letter in the string being uppercase.

Sample Solution

Python Code:

# Define a function 'test' that alternates the case of each letter in a given string.
def test(txt):
    # Initialize an empty string to store the result.
    result_str = ""
    
    # Initialize a boolean variable 's' to determine whether to convert to uppercase or lowercase.
    s = True
    
    # Iterate through each character in the input string 'txt'.
    for i in txt:
        # If 's' is True, convert the character to uppercase; otherwise, convert it to lowercase.
        result_str += i.upper() if s else i.lower()
        
        # Toggle the value of 's' if the character is alphabetic.
        if i.isalpha():
            s = not s
    
    # Return the final result string with alternating case.
    return result_str

# Test cases with different input strings.
str1 = "Python Exercises"
print("Original string: ", str1)
print("After alternating the case of each letter of the said string:")
print(test(str1))

str1 = "C# is used to develop web apps, desktop apps, mobile apps, games and much more."
print("\nOriginal string: ", str1)
print("After alternating the case of each letter of the said string:")
print(test(str1))

Sample Output:

Original string:  Python Exercises
After alternating the case of each letter of the said string:
PyThOn ExErCiSeS

Original string:  C# is used to develop web apps, desktop apps, mobile apps, games and much more.
After alternating the case of each letter of the said string:
C# iS uSeD tO dEvElOp WeB aPpS, dEsKtOp ApPs, MoBiLe ApPs, GaMeS aNd MuCh MoRe.

Explanation:

Here is a breakdown of the above Python code:

Define Test Function (test function):

The "test()" function takes a string as input and alternates the case of each letter.
It initializes an empty string (result_str) to store the final result.
A boolean variable 's' is used to determine whether to convert the next character to uppercase or lowercase.
The function iterates through each character in the input string, converting them accordingly and toggling the value of 's' for alphabetic characters.

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program to alternate the case of each letter in a string, starting with uppercase for the first character.
Write a Python program to transform a string so that its letters alternate between uppercase and lowercase.
Write a Python program to change the case of a string such that the first letter is uppercase and the remaining letters alternate in case.
Write a Python program to output a new string with alternating letter cases while preserving spaces and punctuation.

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Next: Write a Python program to get the Least Common Multiple (LCM) of more than two numbers. Take the numbers from a given list of positive integers.

Python Code Editor:

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