What is a function in Python?In Python, a function is a group of related statements that performs a specific task. Show Nội dung chính
Functions help break our program into smaller and modular chunks. As our program grows larger and larger, functions make it more organized and manageable. Furthermore, it avoids repetition and makes the code reusable. Syntax of Functiondef function_name(parameters): """docstring""" statement(s) Above shown is a function definition that consists of the following components.
Example of a function
How to call a function in python?Once we have defined a function, we can call it from another function, program, or even the Python prompt. To call a function we simply type the function name with appropriate parameters.
Try running the above code in the Python program with the function definition to see the output.
Note: In python, the function definition should always be present before the function call. Otherwise, we will get an error. For example,
DocstringsThe first string after the function header is called the docstring and is short for documentation string. It is briefly used to explain what a function does. Although optional, documentation is a good programming practice. Unless you can remember what you had for dinner last week, always document your code. In the above example, we
have a docstring immediately below the function header. We generally use triple quotes so that docstring can extend up to multiple lines. This string is available to us as the For example: Try running the following into the Python shell to see the output.
To learn more about docstrings in Python, visit Python Docstrings. The return statementThe Syntax of returnreturn [expression_list] This statement can contain an expression that gets evaluated and the value is returned. If there is no expression in the statement or the For example:
Here, Example of return
Output 2 4 How Function works in Python?Working of functions in PythonScope and Lifetime of variablesScope of a variable is the portion of a program where the variable is recognized. Parameters and variables defined inside a function are not visible from outside the function. Hence, they have a local scope. The lifetime of a variable is the period throughout which the variable exists in the memory. The lifetime of variables inside a function is as long as the function executes. They are destroyed once we return from the function. Hence, a function does not remember the value of a variable from its previous calls. Here is an example to illustrate the scope of a variable inside a function.
Output Value inside function: 10 Value outside function: 20 Here, we can see that the value of x is 20 initially. Even though the function This is because the variable x inside the function is different (local to the function) from the one outside. Although they have the same names, they are two different variables with different scopes. On the other hand, variables outside of the function are visible from inside. They have a global scope. We can read these values from inside the function but cannot change (write) them. In order to modify the value of variables outside the function, they must be declared as global variables using the keyword Types of FunctionsBasically, we can divide functions into the following two types:
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