Resource sharing of old boy Python advanced operation and maintenance practical high-quality advanced video tutorials

Python is an object-oriented, interpreted computer programming language invented by Guido van Rossum in 1989. The first public release was released in 1991. Python is purely free software. The source code and interpreter CPython follow the GPL (GNU General Public License) agreement. Python syntax is concise and clear, and one of its features is the mandatory use of white space as statement indentation. Python has rich and powerful libraries. It is often nicknamed the glue language, which can easily connect various modules made in other languages ​​​​(especially C/C++) together. "Old Boy Python Advanced Operation and Maintenance Premium Advanced Video Tutorial" will give you an in-depth understanding of the Python language

Course playback address: http://www .php.cn/course/568.html

The teacher’s teaching style:

The teacher’s lectures are simple, clear and organized, Interlocking, rigorous argumentation, and rigorous structure, using the logical power of thinking to attract students' attention, and using reason to control the classroom teaching process. By listening to the teacher's lectures, students not only learned knowledge, but also received training in thinking, and were also influenced and influenced by the teacher's rigorous academic attitude

The more difficult point in this video is the knowledge of python functions:

Friends who have been exposed to C language must be very familiar with the word function. No matter which programming language it is in, function (of course in some languages Called method, the meaning is the same) all play a vital role. Today let’s learn about function usage in Python.

1. Definition of function

In some programming languages, function declaration and function definition are separated (in these programming languages, function declaration and function definition can appear in different files (such as C language), but in Python, function declaration and function definition are regarded as one. In Python, the basic form of function definition is as follows:

def function(params):
    block    return expression/value

Here are a few points:

　(1) In Python The def keyword is used to define the function without specifying the type of the return value.

　(2) Function parameter params can be zero, one or more. Similarly, function parameters do not need to specify parameter types, because variables in Python are weakly typed, and Python will automatically Maintain its type.

　(3) The return statement is optional. It can appear anywhere in the function body, indicating that the function call execution ends here; if there is no return statement, NONE will be automatically returned. If there is a return statement, but return If there is no expression or value after it, NONE will be returned. Let’s look at two examples:

def printHello():
    print 'hello'
    
def printNum():
    for i in range(0,10):
        print i
    return
        
def add(a,b):
    return a+b
    
print printHello()
print printNum()
print add(1,2)

2. Use of functions

After defining a function, you can use it, but there is one problem that you should pay attention to in Python, that is, in Python Forward references are not allowed, that is, calling the function before it is defined is not allowed. Just look at an example to understand:

print add(1,2)
def add(a,b):    
return a+b

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