Python3中对range()逆序的解释

python 3.6.0 (v3.6.0:41df79263a11, Dec 23 2016, 08:06:12) [MSC v.1900 64 bit (AMD64)] on win32
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>>> range(4)
range(0, 4)

>>> a = range(4)
>>> type(a)
<class 'range'>

>>> b = list(range(4))
>>> b
[0, 1, 2, 3]
>>> type(b)
<class 'list'>

a = range(6)  # list(a): [0, 1, 2, 3, 4, 5]
new = []
for i in reversed(a):
    new.append(i)
print(new)  # [5, 4, 3, 2, 1, 0]

new =[]
for i in range(5, -1, -1):
    new.append(i)
print(new)  # [5, 4, 3, 2, 1, 0]

a=[1,2,4,2,4,5,7,10,5,5,7,8,9,0,3]
a.sort()
last=a[-1]
for i in range(len(a)-2,-1,-1):
    if last==a[i]:
        del a[i]
    else:
        last=a[i]
print(a)            # [0, 1, 2, 3, 4, 5, 7, 8, 9, 10]

a = [1, 2, 4, 2, 4, 5, 7, 10, 5, 5, 7, 8, 9, 0, 3]  # length : 15
a.sort()
print(a)       # [0, 1, 2, 2, 3, 4, 4, 5, 5, 5, 7, 7, 8, 9, 10]
last = a[-1]
print(last)    # 最后一个元素是last,最开始时为10
# 从index=13(倒数第2个)(包含)开始,倒着数,到 index=-1 (不含)
# 或者说:从下标index=13(含),到index=-1(不含)相当于到index=0(含)
for i in range(len(a)-2, -1, -1):
    if last == a[i]:    #  将最后一个元素 分别与 其他元素比较大小
        del a[i]      # 相同就删掉
    else:
        last = a[i]     # 不同就把当前元素赋值传给last
print(a)

range(begin, end, step)

# range(begin, end, 方向)  范围为： [begin, end) 即 [3, 2, 1]
for i in range(3, 0, -1):
    print(i)
print('\n')
# 范围为 [3, 2, 1, 0]
for i in range(3, -1, -1):
    print(i)
 
#========== 结果 ==========#
3
2
1
 
3
2
1
0

for i in reversed(range(10)):
    print(i)
"""
输出结果：
9
8
7
6
5
4
3
2
1
0
"""