Python Learning Notes (3)-control flow, functions

1. Control flow Statements
   If, while, for, break, continue
   from the effect of the final effect, the students have no difference in other languages. The only thing to be aware of is syntax, and Python is so amazing and loving in syntax.
   
   Use of control flow statements
   

   1  whileTrue:2input_number = Int (Raw_input ('Enter an integer'))3 4     ifInput_number = =0:5          Break6 7     elifInput_number% 2 = =0:8         Print 'Input_number:', Input_number9         ContinueTen  One     Print 'Looping ...' A  - Print ' Over'

   (sentiment: In fact, as a programmer, once mastered a programming language, really should not be afraid to learn new language. )
2. Function
   Keyword defining a function: "def":

   1 def SayHello (): 2     Print ' Hello world! ' 3 4

   It is important to note that the function must already be defined before the function is used, that is, the function call is always after the function is defined.
   
   To define a function with parameters:

   1 defSay (message, Times=1, who_say='programe'):2     PrintMessage,who_say * Times3 4Say'Hello')5Say' World', 2)6Say'Hello', who_say='He')

   (Note that parameters that do not have a default value cannot be placed after a parameter with a default value)
   
   It's nice to be here. Provides default values for setting parameters, and can be assigned by keyword. This means that, especially in the case of many parameters, you can only assign values to parameters that need to be assigned, rather than having to pass in the preceding arguments because one of the arguments is placed later.
   
   Python is truly natural and easy to read and understand, such as the code just now, you can read the code semantics probably understand that this statement is: Print the message specified number of times

   Print message * times

   
   Return statement
   You can also use return to end a function in a function, or return a value at the same time. If you do not use the return statement manually, each function will also imply a sentence "return none",none means no value.

3. DocString
   The document string, defined as the first string within the function, is equivalent to a C # document comment, can generate a document, and can be viewed at any time by running "print functionname.__doc__"
   

   1 defPrintmax (x, y):2     " "Prints The maximum of the numbers.3 4 The values must be integers." "5x = Int (x)#Convert to integers, if possible6y =Int (y)7 8     ifX >y:9         PrintX'is maximum'Ten     Else: One         PrintY'is maximum' A  -Printmax (3, 5) - PrintPrintmax.__doc__

Python Learning Notes (3)-control flow, functions