How do you use the “def” keyword in Python?

2 years ago
Liam
2 minutes

In Python, the keyword “def” is used to define functions. Functions are used to encapsulate reusable code blocks, can take parameters, and return results.

Here is the general syntax for the ‘def’ keyword:

def function_name(parameters):
    # 函数体
    # 可执行的代码块
    return value
  1. You can customize the function name after the “def” keyword as needed.
  2. Parameters are a list of variables used to pass data to a function, and can be defined as needed to pass multiple pieces of data.
  3. Colon (:) marks the end of a function definition, and the indented code block following it is the body of the function.
  4. You can write any valid Python code inside the function body to perform specific operations.
  5. The return statement is used to specify the return value of a function and can optionally return a result. If there is no return statement, the function will default to returning None.

Here is a simple example showing how to define a function using ‘def’ and call it:

def greet(name):
    print("Hello, " + name + "!")

greet("Alice")  # 输出：Hello, Alice!
greet("Bob")    # 输出：Hello, Bob!

In the example above, “greet” is the name of the function that takes a parameter “name” and prints a greeting message within the function body. Later on, the greet function is called twice with different parameters, resulting in different outputs.

This is just a simple example; in practical applications, functions can perform more complex operations by taking multiple parameters and returning specific results.

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