Add demo regex

Author: hxuhack

README.md

@@ -6,7 +6,7 @@
 | 周 | 内容 | 资料 | 代码 |
 |---|---|---|---|
 | 1 | 使用Python编写神经网络 | [课件](notes/L1-使用python编写神经网络.pdf) | [factorial-relu](code/l1-factorial-relu.py), [factorial-sigmoid](code/l1-factorial-sigmoid.py) |
-| 2 | Python程序的解析和运行 | [课件](notes/L2-Python程序的解析和运行.pdf) | [relu](code/l2-relu.py), [pytool](code/l2-pytool.py) |
+| 2 | Python程序的解析和运行 | [课件](notes/L2-Python程序的解析和运行.pdf) | [regex](code/l2-regex.py), [pytool](code/l2-pytool.py), [relu](code/l2-relu.py) |
 | 3 | Python与Native Code交互 | | | 
 | 4 | Python多线程 | | | 
 | 5 | 课堂反转 | |

code/l2-regex.py

@@ -0,0 +1,15 @@
+import re
+
+pattern_name = r'[A-Za-z_][A-Za-z0-9_]*'
+pattern_number = r'\d+(?:\.\d+)?'
+
+examples = ['ABC', 'aBC', 'x = 123', 'var1 = 3.14']
+
+for text in examples:
+    names = re.findall(pattern_name, text)
+    numbers = re.findall(pattern_number, text)
+
+    print(f"Text: {text!r}")
+    print(f"Names: {names}")
+    print(f"Numbers: {numbers}")
+    print("-" * 40)