编程案例：
```
import urllib.parse
def urlencode_example():
# 定义一个包含特殊字符的字符串
original_string = "Hello World!@#$%^&*()_+=-{}[]|:;\"'<>,.?/~`"
# 使用urlencode函数对字符串进行编码
encoded_string = urllib.parse.quote(original_string)
# 打印编码后的字符串
print("Encoded String:", encoded_string)
# 使用urldecode函数对编码后的字符串进行解码
decoded_string = urllib.parse.unquote(encoded_string)
# 打印解码后的字符串
print("Decoded String:", decoded_string)
# 调用示例函数
urlencode_example()
运行上述代码，将输出：
Encoded String: Hello%20World%21%40%23%24%25%5E%26%2A%28%29_%2B%3D-%7B%7D%5B%5D%7C%3A%3B%22%27%3C%3E%2C.%3F%2F~%60
Decoded String: Hello World!@#$%^&*()_+=-{}[]|:;\"'<>,.?/~`
