Python Learning Note four: Process Control

Conditional statements:

#以缩进来区分表示同一范围.

1 #Coding=utf82 #Example 1:if basic usage3 4Flag =False5Name ='Luren'6 ifName = ='python':#determine whether the variable is ' python '7Flag = True#set flag to True when condition is established8     Print 'Welcome Boss'    #and output Welcome information9 Else:Ten     PrintName#output variable name when condition is not valid

Multiple judgments:

1 #Coding=utf82 #Example 2:elif usage3 4num = 55 ifnum = = 3:#determine the value of Num6     Print 'boss'        7 elifnum = = 2:8     Print 'User'9 elifnum = = 1:Ten     Print 'worker' One elifNum < 0:#value is less than zero output A     Print 'Error' - Else: -     Print 'Roadman'     #output when conditions are not true

Python does not support switch statements

1 #Coding=utf82 #example 3:IF statement multiple conditions3 4num = 95 ifNum >= 0 andNum <= 10:#determine if the value is between 0~106     Print 'Hello'7>>> Hello#Output Results8 9num = 10Ten ifNum < 0ornum > 10:#determine if the value is less than 0 or greater than One     Print 'Hello' A Else: -     Print 'undefine' ->>> undefine#Output Results the  -num = 8 - #determine if the value is between 0~5 or 10~15 - if(Num >= 0 andNum <= 5)or(Num >= 10 andNum <= 15):     +     Print 'Hello' - Else: +     Print 'undefine' A>>> undefine#Output Results

Same line, similar to IDL

1 #  2  34  5if (var  print" Value of Expression is " 6  7 Print " Good bye! "

Loop statement:

While

 1  #   2  3  Count = 0  4  while  (Count < 9 5  print   '  

while ... else

 1  #   2  3  Count = 0  4  while  (Count < 9 5  print   '  

1 # !/usr/bin/python 2 3 flag = 145while theprint'Given flag is really true! ' 6 7 Print " Good bye! "

While loop nesting

1 #Coding=utf-82 #!/usr/bin/python3 4i = 25  while(I < 100):6j = 27     while(J <= (i/j)):8       if  not(I%J): Break9j = j + 1Ten    if(J > i/j):PrintI"is prime" Onei = i + 1 A  - Print "Good bye!"

For

traverse Any sequence of items, lists, or strings

For I in sequence

Statements (s)

1 #!/usr/bin/python2 3  forLetterinch 'Python':#First Example4    Print 'Current Letter :', Letter5 6Fruits = ['Banana','Apple','Mango']7  forFruitinchFruits#Second Example8    Print 'Current fruit:', Fruit9 Ten Print "Good bye!"

>

Current letter:pcurrent letter:ycurrent letter:tcurrent letter:hcurrent letter:ocurrent letter:ncurrent Fruit : Bananacurrent fruit:applecurrent Fruit:mangogood bye!

Index

1 #!/usr/bin/python2 3Fruits = ['Banana','Apple','Mango']4  forIndexinchrange (len (fruits)):5    Print 'Current fruit:', Fruits[index]6 7 Print "Good bye!"

The built-in function Len () and range (), function Len () returns the length of the list, which is the number of elements. Range returns the number of a sequence.

For .... else ... (For loop nesting)

1 #!/usr/bin/python2 3  forNuminchRange (10,20):#To iterate between4     forIinchRange (2,num):#To iterate on the factors of the number5       ifNum%i = = 0:#To determine the first factor6j=num/i#To calculate the second factor7          Print '%d equals%d *%d'%(NUM,I,J)8           Break #to move to the next number, the #first for9    Else:#else part of the loopTen       PrintNum'Is a prime number'

Break jumps out of the loop continue out of this loop pass empty statement, is to maintain the integrity of the program structure.

1 #!/usr/bin/python2 3  forLetterinch 'Python': 4    ifLetter = ='h':5       Pass6       Print 'This is pass block'7    Print 'Current Letter :', Letter8 9 Print "Good bye!"

Python Learning Note four: Process Control