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.

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第二个参数严格匹配一个非字母和数字组成的字符串，该字符串后面依次为空格、整数、另一个空格，最后是一个实数。

The second argument strictly matches a non-alphanumeric string followed by a space followed by an integer followed by another space and finally a real number.

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另一方面，EBCDIC中的排序序列则是：空格、小写字符、大写字符和数字值。

On the other hand, the collating sequence in EBCDIC is: space, lower case characters, upper case characters, and numeric values.

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