python之函数用法xrange()

# -*- coding: utf-8 -*-
#python 27
#xiaodeng
#python之函数用法xrange()


#xrange()
#说明：返回一个生成器
#xrange做循环的性能比range好,尤其是返回很大的时候.除非要返回一个列表,则用range.
‘‘‘
class xrange(object)
 |  xrange(stop) -> xrange object
 |  xrange(start, stop[, step]) -> xrange object
 |  
 |  Like range(), but instead of returning a list, returns an object that
 |  generates the numbers in the range on demand.  For looping, this is 
 |  slightly faster than range() and more memory efficient.
‘‘‘



#案例
x= xrange(5)            #xrange(5)-> xrange对象
print list(x)           #[0, 1, 2, 3, 4]