Python Beginners Guide摘抄

就当是学计算机英语

Beginners Guide　　http://www.afterhoursprogramming.com/tutorial/Python/Overview/

Python is used as a server side language.

it can output HTML.

Python is space sensitive.

it is one of the simplest looking languages.?

Two ways to comment in Python:

Single line: #comment

Multiple line:

'''

comments

'''

Variables are awesome asset to the dynamic world of the web.?

Python interprets and declares variables for you when you set them equal to a value.

cast type to another type:int(variable) 　　str(variable)　　float(variable)

Python operations:

print(3/4)#0.75

print(3**4)#3 to the fourth power

print(3//4)#floor division

 % is called the modulus operator.

= is called assignment operator.

we are programmers and we are proud to be called lazy.

The if statement is a conditional that ,when it is satisfied ,activates some part of code.

Python's else if is shortened into elif.

If statements are generally coupled with variables to produce more dynamic content.

Python's syntax is a lot cleaner then other languages ,this also means it is very picky and tends to bite beginners with errors.

 It is necessary to define functions before they are called.

Python does support global variables without you having to explicitly express that they are global variables.

The do-while loop isn't in Python.

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Common String Methods in Python

• stringVar.count('x') - counts the number of occurrences of 'x' in stringVar
• stringVar.find('x') - returns the position of character 'x'　　  return -1 if 'x' is not contained in the stringVar
• stringVar.lower() - returns the stringVar in lowercase (this is temporary)
• stringVar.upper() - returns the stringVar in uppercase (this is temporary)
• stringVar.replace('a', 'b') - replaces all occurrences of a with b in the string这里的描述不准确，容易引起误会。这句话其实描述的是replace函数的返回值，strip也是
• stringVar.strip() - removes leading/trailing white space from string

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A negative number in an index means that you want python to calculate the index starting from the end and moving towards the front aka backwards.

Common List Methods

• .append(value) - appends element to end of the list
• .count('x') - counts the number of occurrences of 'x' in the list
• .index('x') - returns the index of 'x' in the list
• .insert('y','x') - inserts 'x' at location 'y'
• .pop() - returns last element then removes it from the list
• .remove('x') - finds and removes first 'x' from list
• .reverse() - reverses the elements in the list      逆序
• .sort() - sorts the list alphabetically in ascending order, or numerical in ascending order
  • 排序，同时包含数字和字符串时不能排序

  • 　　slist.sort()
    TypeError: '<' not supported between instances of 'str' and 'int'

 Python 是解释型语言

Tuple的格式就像JSON

转载于:https://www.cnblogs.com/afraidToForget/p/6576756.html