Check if a String is Empty

1. The Challenge: Empty String Detection

Create a function is_empty(s) that returns True if a string is empty and False otherwise.

2. Why It Matters

Validating empty text input prevents processing null values when handling form submissions or user comments.

3. The Python Solution

In Python, an empty string "" is falsy. You can check not s or check if len(s) == 0:

def is_empty(s):
    return len(s) == 0

# Pythonic Truthiness Alternative
def is_empty_pythonic(s):
    return not s

# Testing our function
print(is_empty(""))      # Output: True
print(is_empty(" "))     # Output: False (contains space character!)
print(is_empty("a"))     # Output: False

4. Empty String Truthiness Model

• "" (Length 0) evaluates to False in boolean context.
• " " (Space character, length 1) evaluates to True. To check if a string is only whitespace, use not s.strip().

5. Common Mistakes

• Confusing Empty String with Space: " " is NOT an empty string! If you want whitespace-only strings to count as empty, call not s.strip().

6. Next Steps

Use not s for Pythonic empty checks. Next, let's compare string lengths!