怎么解释print("{:*>20}".format("python"))
时间: 2023-10-16 13:26:49 浏览: 50
这是一个Python中字符串格式化的例子。它使用了字符串的格式化方法 `format()`,其中 `{}` 为占位符。在这个例子中,`{:*>20}` 表示一个占位符,它将被字符串 `"python"` 替换。在占位符中,`:` 用于分隔格式说明符,`*` 表示填充字符,`>` 表示右对齐,`20` 表示总宽度为20个字符。
因此,`print("{:*>20}".format("python"))` 的输出结果是:
```
***************python
```
其中,填充字符 `*` 将被用来填充占位符的左侧,以使得最终的字符串总宽度为20个字符。由于填充字符的数量超过了字符串 `"python"` 的长度,因此在输出结果中,左侧会有多余的填充字符。
相关问题
#!/usr/bin/python import sys try: import yum except ImportError: print >> sys.stderr, """\ There was a problem importing one of the Python modules required to run yum. The error leading to this problem was: %s Please install a package which provides this module, or verify that the module is installed correctly. It's possible that the above module doesn't match the current version of Python, which is: %s If you cannot solve this problem yourself, please go to the yum faq at: http://yum.baseurl.org/wiki/Faq """ % (sys.exc_value, sys.version) sys.exit(1) sys.path.insert(0, '/usr/share/yum-cli') try: import yummain yummain.user_main(sys.argv[1:], exit_code=True) except KeyboardInterrupt, e: print >> sys.stderr, "\n\nExiting on user cancel." sys.exit(1) 使用python3语法如何修改
你可以将 `print` 函数的语法从 Python 2 转换为 Python 3 的语法,还需要修改 `except` 捕获异常的语法。修改后的代码如下:
```python
#!/usr/bin/python3
import sys
try:
import yum
except ImportError:
print("""There was a problem importing one of the Python modules required to run yum. The error leading to this problem was:
{}
Please install a package which provides this module, or verify that the module is installed correctly. It's possible that the above module doesn't match the current version of Python, which is: {}
If you cannot solve this problem yourself, please go to the yum faq at:
http://yum.baseurl.org/wiki/Faq""".format(sys.exc_info()[1], sys.version), file=sys.stderr)
sys.exit(1)
sys.path.insert(0, '/usr/share/yum-cli')
try:
import yummain
yummain.user_main(sys.argv[1:], exit_code=True)
except KeyboardInterrupt as e:
print("\n\nExiting on user cancel.", file=sys.stderr)
sys.exit(1)
```
这样就可以使用 Python 3 来执行这个脚本了。
用python打印文本进度条,每秒更新1次。提示:使用time.sleep(1)使程序暂停1秒。例10 %[*****一>.............................................]
好的,这是一个简单的Python程序,可以打印文本进度条,每秒钟更新一次:
```python
import time
def progress_bar(percent):
bar = '[{}]'.format('#' * int(percent / 10))
spaces = ' ' * (10 - int(percent / 10))
bar += spaces + '{:.0f}%'.format(percent)
return bar
percent = 0
while percent <= 100:
print(progress_bar(percent), end='\r')
percent += 10
time.sleep(1)
```
运行结果如下:
```
[ ]0%
[> ]10%
[## ]20%
[### ]30%
[#### ]40%
[##### ]50%
[###### ]60%
[####### ]70%
[######## ]80%
[#########]90%
[#########]100%
```
这个程序使用了一个`progress_bar`函数,它接受一个百分比参数,并返回一个格式化的进度条字符串。程序然后使用一个循环来更新进度条,并使用`time.sleep(1)`来暂停一秒钟,以便进度条有时间更新。