Python uppercase converter: Handle empty input

Last update on April 23 2025 12:51:31 (UTC/GMT +8 hours)

5. Uppercase Conversion with None Check

Write a Python program that takes a user's input and converts it to uppercase. If the input is empty, return None.

Sample Solution:

Code:

def convert_to_uppercase(input_string):
    if not input_string:
        return None
    
    return input_string.upper()

def main():
    try:
        str_input = input("Enter a string: ")
        result = convert_to_uppercase(str_input)
        
        if result is None:
            print("Input is empty.")
        else:
            print("Uppercase result:", result)
    except Exception as e:
        print("An error occurred:", e)

if __name__ == "__main__":
    main()

Output:

Enter a string: sdfsd
Uppercase result: SDFSD

Enter a string: 
Input is empty.

In the above exercise, the "convert_to_uppercase()" function checks if the input string is empty. If it's empty, it returns None. Otherwise, it converts the input string to uppercase using the "upper()" method and returns the result. A user input is taken and the result is printed using the "main()" function.

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program that converts user input to uppercase, returning None if the input is an empty string.
Write a Python function to transform a string to uppercase and return None when given an empty input, using a single-line conditional expression.
Write a Python script to prompt for a string, convert it to uppercase if non-empty, and print "None" if the string is empty.
Write a Python program that processes a list of inputs, converting each to uppercase or returning None for empty strings.

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