Python program to find number of local variables in a function

In this article, we will learn how to find the number of local variables in a function using Python's built-in code object attributes.

Problem statement ? We are given a function, and we need to display the number of local variables defined within that function.

Understanding Local Variables

Local variables are variables that are defined inside a function and can only be accessed within that function's scope. Python stores information about functions in code objects, which include the count of local variables.

Using __code__.co_nlocals

Every function in Python has a __code__ attribute that contains a code object. The co_nlocals attribute of this code object returns the number of local variables in the function.

Example 1: Basic Function with Local Variables

# Function with multiple local variables
def scope():
    a = 25.5
    b = 5
    str_ = 'Tutorialspoint'

# Check number of local variables
print("Number of local variables available:", scope.__code__.co_nlocals)

Number of local variables available: 3

Example 2: Comparing Functions

Let's compare an empty function with a function containing local variables ?

# Empty function
def empty():
    pass

# Function with local variables
def scope():
    a, b, c = 9, 23.4, True
    text = 'Tutorialspoint'

# Check local variables count
print("Empty function local variables:", empty.__code__.co_nlocals)
print("Scope function local variables:", scope.__code__.co_nlocals)

Empty function local variables: 0
Scope function local variables: 4

Example 3: Function with Parameters

Parameters are also counted as local variables ?

# Function with parameters and local variables
def calculate(x, y):
    result = x + y
    message = "Calculation complete"
    return result

print("Function with parameters local variables:", calculate.__code__.co_nlocals)

Function with parameters local variables: 4

Key Points

• Function parameters are counted as local variables
• Variables assigned inside the function are local variables
• The co_nlocals attribute counts all local variables, including parameters
• Empty functions or functions with only pass have zero local variables

Conclusion

Use the __code__.co_nlocals attribute to find the number of local variables in any Python function. This includes both function parameters and variables assigned within the function scope.