sys.stdout.write与sys.sterr.write(三)

目标：

　　1.使用sys.stdout.write模拟"|"的顺时针变化— | / 

　　2.使用sys.stderr.write模拟"|"的顺时针变化— | /

1.sys.stdout.write模拟"|"的顺时针变化

代码如下：

[root@localhost python]# cat animation.py

#!/usr/bin/env python
#coding:utf8

import sys,time

for i in xrange(10):
    for ch in '-\|/':
        print '%-20s%s
' % ('waiting...', ch)
        #sys.stdout.write('%-20s%s
' % ('waiting...', ch))
        sys.stdout.flush()
        time.sleep(0.2)

•运行代码，测试效果

[root@localhost python]# python animation.py

waiting...          -
waiting...          
waiting...          |
waiting...          /
waiting...          -
waiting...          
waiting...          |
waiting...          /
waiting...          -
waiting...          
waiting...          |
waiting...          /
waiting...          -
waiting...          
waiting...          |
waiting...          /
waiting...          -
waiting...          
waiting...          |
waiting...          /
waiting...          -
waiting...          
waiting...          |
waiting...          /
waiting...          -
waiting...          
waiting...          |
waiting...          /
waiting...          -
waiting...          
waiting...          |
waiting...          /
waiting...          -
waiting...          
waiting...          |

*提示：上述代码使用print是为了打印代码的过程，将print代码行注释，打开sys.stdout.write代码行，重新运行，即可看到"|"顺时针变化的效果。

2.sys.stderr.write模拟"|"的顺时针变化

代码如下：

[root@localhost python]# cat animation.py

#!/usr/bin/env python
#coding:utf8

import sys,time

for i in xrange(10):
    for ch in '-\|/':
        #print '%-20s%s
' % ('waiting...', ch)
        sys.stderr.write('%-20s%s
' % ('waiting...', ch))
        #sys.stdout.flush()
        time.sleep(0.2)

•运行代码，测试效果

*提示：使用sys.stderr.write没有缓存，注释sys.stdout.flush()