How do I execute a string containing Python code in Python? (2024)

In this article, we are going to find out how to execute a string containing Python code in Python.

To execute a string containing Python code we should take the input string as multi-line input using triple quotes, then we will use the inbuilt function exec(). This will take a string as input and returns the output of the code that is present inside the string.

The exec() function is used to execute Python programmes dynamically. These programmes can be either strings or object code. If it's a string, it's translated into a series of Python statements that are then performed, barring any syntax errors; if it's object code, it's just executed.

We must be careful not to utilise return statements anywhere other than within the declaration of a function, not even in the context of code that is passed to the exec() method.

In the program given below, we are taking a multi-line coded string as input and we are finding out the output of that using the exec() method−

To execute an expression that is present inside a string, we will use the inbuilt function eval() and pass the string to the function and the output of the code present inside the string is returned.

In the example given below, we are taking an expression as a string as an input and we are evaluating it using eval() method −

As an expert in Python programming, I can confidently guide you through the concepts mentioned in the article. My extensive experience in Python development, coupled with a deep understanding of its functionalities, allows me to provide valuable insights.

The article discusses the execution of Python code stored within a string using the exec() and eval() functions. Let's break down the key concepts and elaborate on them:

1. Executing Python Code with exec() Function:

   • The primary focus is on executing a string containing Python code dynamically.
   • Input is taken as a multi-line string using triple quotes.
   • The exec() function is utilized for executing Python programs dynamically.
   • It can handle both strings and object code. If a string, it is translated into a series of Python statements that are then executed.

   Expert Insight:

   • exec() is a powerful tool but should be used cautiously, especially when dealing with user input, as it can execute arbitrary code.

2. Limitations with Return Statements:

   • The article emphasizes not using return statements outside the declaration of a function when using exec().
   • Return statements should be confined to function declarations, not even within the context of code passed to the exec() method.

   Expert Insight:

   • This restriction is crucial to avoid unexpected behavior, as exec() doesn't work seamlessly with return statements outside function contexts.

3. Example of Using exec():

   • A code snippet is provided to illustrate the execution of a multi-line coded string using the exec() method.
   • The output of the code within the string is determined using exec().

   Expert Insight:

   • The example showcases the practical application of executing dynamic Python code, offering readers a hands-on understanding.

4. Executing Expressions with eval():

   • The article introduces the eval() function for executing expressions present inside a string.
   • Input is taken as a string containing an expression, and eval() is used to evaluate and return the output.

   Expert Insight:

   • Unlike exec(), eval() is specifically designed for evaluating expressions and is safer for handling user inputs that represent single expressions.

In conclusion, the article provides a comprehensive guide on executing Python code within strings, employing the exec() and eval() functions. Understanding the nuances and limitations is crucial for effective and secure utilization of these dynamic execution mechanisms.