Execute a String of Code in Python

Last Updated : 10 Jan, 2025

Sometimes, we encounter situations where a Python program needs to dynamically execute code stored as a string. We will explore different ways to execute these strings safely and efficiently.

Using the exec function

exec() function allows us to execute dynamically generated Python code stored in a string. It is the most straightforward and commonly used method for this purpose.

code = "x = 5\ny = 10\nprint(x + y)"
exec(code)

Output

Explanation:

exec() function takes the string of code as an argument and executes it as Python code.
variables x and y are created and their sum is printed.
This method is simple and works well for executing multiple lines of code stored as a string.

Let’s explore some more methods and see how we can execute a string of code in Python.

Table of Content

Using eval()
Using compile()
Using subprocess module

Using eval()

eval() function can execute a single expression stored in a string and return its result. It is more limited compared to exec() but can be useful for evaluating expressions.

code = "5 + 10"
res = eval(code)
print(res)

Output

Explanation:

eva() function evaluates the string as a Python expression and returns the result.
This method is ideal for scenarios where we only need to execute and get the result of a single expression.

Using compile()

compile() function can be used to compile a string of code into a code object, which can then be executed using exec() or eval(). This is useful for advanced use cases where we need more control.

code = "x = 5\ny = 10\nprint(x + y)"
compiled_code = compile(code, '<string>', 'exec')
exec(compiled_code)

Output

Explanation:

compile() function converts the string of code into a code object.
exec() function is then used to execute the compiled code object.
This method is useful for scenarios where we need to compile the code once and execute it multiple times.

Using subprocess module

If we want to execute the code in a separate process, we can use the subprocess module. This is more suitable for executing standalone scripts or commands.

import subprocess

code = "print(5 + 10)"
subprocess.run(["python3", "-c", code])

Output

Explanation:

The subprocess.run function is used to execute the string of code as a separate Python process.
The -c flag allows us to pass the code string directly to the Python interpreter.
This method is useful when we need isolation or want to execute the code in a separate environment.