How are arguments passed by value or by reference?

In programming, when a function is called with arguments, those arguments can be passed either by value or by reference. Here's how each method works:

Passing by value

When an argument is passed by value, a copy of the argument's value is created and passed to the function. This means that any changes made to the argument within the function will not affect the original value of the argument outside of the function. In other words, the original value of the argument is preserved.

Passing by reference

When an argument is passed by reference, a reference or pointer to the argument is passed to the function. This means that any changes made to the argument within the function will affect the original value of the argument outside of the function. In other words, the original value of the argument can be modified.

In Python, all function arguments are passed by reference, but the behavior can be different depending on the type of object being passed. Mutable objects like lists and dictionaries are passed by reference, which means that changes made to the object within the function will affect the original object outside of the function. Immutable objects like integers and strings are passed by value, which means that a copy of the object is passed to the function and changes made to the object within the function will not affect the original object outside of the function.

In summary, the way arguments are passed to a function can affect how the function operates on those arguments and how those changes affect the original data. Understanding the difference between passing by value and passing by reference is important for writing effective and reliable code.