Python:制御文

//Python             ( java  {}    )
//  
>>> a = 11
>>>while a>10 :
>>>		a = 10  //
>>>		print a //               while 
//while(a>10){
//	a = 10
//	print a
//}
--------------------------------------
//    
>>> a = 10
>>> if a >10 :
>>>		print a
>>> elif a<10 :
>>> 	print 10
>>> else :
>>>		print 0
--------------------------------------
//for    
>>> a=['nana','dandan']
>>> for x in a :
>>>		print x
//for+if 
//         a copy
>>> a=['nana','dandan']
>>> for x in a[:]:
>>>		if len(x)>4 :
>>>			a.insert(0,x)
>>> a
['dandan','nana','dandan']
----------------------------------------
//range()   :           
>>>range(10)
[0,1,2,3,4,5,6,7,8,9]
>>>range(1,5)
[1,2,3,4]

//      
>>> a = ['Mary', 'had', 'a', 'little', 'lamb']
>>> for i in range(len(a)):
...     print i, a[i]

//   java  for    ：
for(int i=0;i<a.length;i++){
	System.out.println(i+""+a[i]);
}

//break continue  java   
//Python for   ，      else
>>> for n in range(2, 10):
...     for x in range(2, n):
...         if n % x == 0:
...             print n, 'equals', x, '*', n/x
...             break
...     else:
...         // loop fell through without finding a factor
...         print n, 'is a prime number'
...
2 is a prime number
3 is a prime number
4 equals 2 * 2
5 is a prime number
6 equals 2 * 3
7 is a prime number
8 equals 2 * 4
9 equals 3 * 3
-----------------------------------
//pass  ，pass      ...
-----------------------------------
//    
def fib(n):
"""        """ //         
	a,b=0,a //       ，      
	while b<n
		print b,
		a,b=b,a+b
					//           return，   None

fib(10) //    

//                    。                   
"""       ，           ，                     (   java     )

       :
     ，           ，        ，        。
  ，           ，             （      global     ）。"""


//   
>>> def fib2(n): // return Fibonacci series up to n
...     """Return a list containing the Fibonacci series up to n."""
...     result = []
...     a, b = 0, 1
...     while b < n:
...         result.append(b)    // see below
...         a, b = b, a+b
...     return result
...
>>> f100 = fib2(100)    // call it
>>> f100                // write the result
[1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]
//return            ，       return    None。          None 。



//    
//1、        
>>> def d(name,age=20,sex='woman'):
>>>		print name,age,sex
>>> d('dd')
dd 20 woman
>>> d('dd',25)
dd 25 woman
>>> d('dd','man') //      ，        dd 20 woman
dd man woman

//                 
>>> i = 5
>>> def f(arg=i) //            
>>>		print arg
>>> i = 6
>>> f()
5 //  
//              ，             ，
//    、          ，       
>>> def f(a, L=[]):
>>>    L.append(a)
>>>    return L
>>> f(1)
[1]
>>> f(2)
[1,2]
>>> f(3)
[1,2,3]
//                      ，              ： 
>>> def f(a, L=None):
>>>    if L is None: //    None 
//		if L ==None
>>>        L = []
>>>    L.append(a)
>>>    return L