2025py重学计划

Day 1

写一个 CLI 工具，输入姓名打印问候语

v1 cat  echo.py 
name = 'evan'
print( name + "  have a good day")

v2
➜  py2025 cat echo.py 
name = input("please input your name")
print( name + "  have a good day")

 py  echo.py 
please input your name evan
 evan  have a good day
➜  py2025 cat echo.py 


v3
import sys
if  len(sys.argv) < 2:
    print("Usage: python echo.py <name>")
else:
    name = sys.argv[1]
    print(f"Hi,  {name}    have a good day")

➜  py2025 py  echo.py 
Usage: python echo.py <name>
➜  py2025 py  echo.py  evan
Hi,  evan    have a good d