将一个数组逆序输出,用第一个与最后一个交换。
#!/usr/bin/python
# -*- coding: UTF-8 -*-
if __name__ == '__main__':
a = [9,6,5,4,1]
N = len(a)
print a
for i in range(len(a) / 2):
a[i],a[N - i - 1] = a[N - i - 1],a[i]
print a
以上实例输出结果为:
[9, 6, 5, 4, 1]
[1, 4, 5, 6, 9]
拓展:
原本文件中是abcd,想把这四行按照dcba的顺序写进一个新文件
解决:
先读取文件到列表,然后对列表逆序,然后循环写入到新的文件
content = []
with open("name.txt" ) as f:
for row in f.readline():
content.append(row)
content.reverse()
with open("name1.txt","w" ) as f:
for row in content:
f.write(row)
f.write("\n")