. NET Programmer's Python basic tutorial learning----judging conditions and loops [fourth day]

Learn about Python's judging conditions and looping operations today.

A. Boolean variable:

The bool variable must be understood before learning the criteria, and in Python the bool variable is similar to the C language, with a larger difference from. NET, where the following focus needs to be remembered.

False, ' ', 0, (), [],{},none is empty, while true,12, ' Hello ', [1] These are all true. In fact, it can be simply understood as, none is false, there is both true

　　　　

BOOL (True) True BOOL (0) False BOOL (1) True BOOL (') False BOOL ('123') True BOOL ([]) False

Two. Use of IF.

　　　　

The

Note:if is separated by the: number, which is equivalent to the C # and C language {} separated by the interval number for the included code snippet. For example, the third line print ' minor is a sub-method of if (age<18), then you need to empty a few spaces in front.

 - if (age<):     ' Young People ' elif (Age <):     ' Adult ' Else :     ' elderly ' Output: ' Adult '

　　　　

 - if (age<):     if (age>):         ' Adult '

Three. Use of the while:

1  while x<=:    print x    x+ =1

Four. For usage:

　　

names = ['Frank','Loch','Vincent' ,'Cain'] for in names:    print name 

Five. Assertion usage: When the assertion is used primarily for testing. If the assertion does not pass, it will be an error.

>>> assert age< >>>assert age<9   # The first assertion passed. The second assertion did not pass, so the error was made.  Traceback (recent):"<pyshell#23>"1 in <module>    assertAge <9assertionerror

Six. Comprehensive use.
1. Below is a list of the numbers that are taken out of the list:

　　　　

 myList = [  frank  , "  bob  , 

2. Print out the Yang Hui triangle: 10-layer Yang Hui triangle, first declare a two-dimensional array, because you cannot use the for (int index;index<10;index++) as C or C + +, I chose a double loop with while

　　　　

RowIndex =1columnindex=0myList= [[1,0,0,0,0,0,0,0,0,0],[1,0,0,0,0,0,0,0,0,0],[1,0,0,0,0,0,0,0,0,0],[1,0,0,0,0,0,0,0,0,0],[1,0,0,0,0,0,0,0,0,0],[1,0,0,0,0,0,0,0,0,0],[1,0,0,0,0,0,0,0,0,0],[1,0,0,0,0,0,0,0,0,0],[1,0,0,0,0,0,0,0,0,0],[1,0,0,0,0,0,0,0,0,0]]print mylistprint (mylist[9][9]) whileRowIndex <Ten:     whileColumnIndex <=RowIndex:if(rowindex==1): mylist[1][0]=1mylist[1][1]=1       Else:           if(columnindex==rowIndex): Mylist[rowindex][columnindex]=1           Else: Mylist[rowindex][columnindex]=mylist[rowindex-1][columnindex-1]+mylist[rowindex-1][columnindex] ColumnIndex+=1columnindex=0RowIndex+=1 Line="' forRowinchmyList: forValinchrow:if(val!=0): Line= line + str (val) +' 'Print Line line="'

Operation Result:
1
1 1
1 2 1
1 3 3 1
1 4 6) 4 1
1 5 10 10 5 1
1 6 15 20 15 6 1
1 7 21 35 35 21 7 1
1 8 28 56 70 56 28 8 1
1 9 126 126 9 1 

　　　　

　　　　

　　

　　　　

　　　　

. NET Programmer's Python basic tutorial learning----judging conditions and loops [fourth day]