这段代码接受来自用户的受感染数据，检查要打印的字符只有字母和数字字符以及空格符，以此来提供安全保护。

This piece of code takes up tainted data from the user, ensuring protection as it checks that the characters to be printed are only alphanumeric characters and Spaces.

youdao

在调查中(如：日记)用于代表回复的数字或字母。为答案设置代码可以使计算机进行数据处理。

The Numbers or letters used to represent responses in a survey instrument like a diary. Coding the responses allows computers to manipulate the data.

youdao