Placeholder Variable in Python
What is a Placeholder Variable?
A placeholder variable in Python is a temporary variable used to represent a value that will be assigned later or is not yet known. It is often used as a dummy variable to hold a place in code where the actual value will be substituted in the future.
Common Use Cases
- Placeholder variables are often used in loops or functions where the value is not immediately needed.
- They are also used to ignore specific values during unpacking or iteration.
Examples
Example 1: Using a Placeholder in a Loop
for _ in range(5):
print("Hello, World!")
Here, the underscore (_) is used as a placeholder variable to indicate that the loop variable is not needed.
Example 2: Ignoring Unwanted Values
x, _, y = (1, 2, 3)
print(x, y) # Output: 1 3
In this example, the underscore (_) is used to ignore the second value during unpacking.
Example 3: Placeholder in Function Definitions
def calculate(a, b, _):
return a + b
result = calculate(10, 20, 30)
print(result) # Output: 30
Here, the third parameter is a placeholder and is not used in the function.
