Process Control Introduction

A, if determined

Role: like people make different behaviors for different situations.

Code block: the same indentation level code

The basic syntax:

A grammar 

　　if         Condition: 

　　　　　　Code 1 

　　　　　　Code 2 

　　　　　　Code 3

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Syntax two

if        Condition: 

　　　　　　Code 1 

　　　　　　Code 2 

　　　the else : 

　　　　　　Code 1 

　　　　　　Code 2

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Three Grammatical

         if    Condition: 

　　　　　　Code 1 

　　　　　　Code 2 

　　　elif conditions:                                                                                   

　　　　　　Code 1 

　　　elif conditions: 

　　　　　　code 1 is 

　　　the else : 

　　　　　　Code 1 
# elif can use the N

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Syntax four if nested

　     if Condition 1: 

　　　　　　if Condition 2: 

　　　　　　　　　　Code 1 

　　　　　　　　　　Code 2 

　　　　　　the else : 

　　　　　　　　　　code 1 is 

　　　the else : 

　　　　　　Code 1

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 Two, while circulation

1. What is the cycle?

The cycle is repeated to do something

 

BREAK : directly out the entire loop

the Continue : the end of this cycle, to enter the next cycle

 

The basic syntax: 

while    条件:

　　　　code1

　　　　code2

　　　　code3

　　　　code4

　　　　code5
            

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while nesting

while  True:

　　 while True:

　　　　break

break

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while also and if nested statement

 

while else:

If the normal end of the while loop, instead of using the break ended, will be the implementation of the sub-code else

 

Out while the two methods of loop

1. while using the inner loop break

2. while modifying the value of the loop condition the condition becomes a logic value False

 

Three, for circulation 

  The power of the for loop that does not depend on the index value.

The basic syntax

     for the variable name in the type of container: 
            Code 1, 
            Code 2, 
            Code 3, 
            Code 4,

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Container type: can accommodate a plurality of types of data can be obtained by a container type length len ().

 

ps: the difference in the range of Python2 and Python3

Python2 in

　　　　The return value is a list of 1.range

　　　　2.xrange is in the range Python3

Python3 the range is an iterator, get value when needed.