Message Digests are secure, one-way hash functions that convert arbitrary length data into fixed-length check sum / hash code.

消息摘要是一个安全的、单向的哈希函数，把任意长度的数据转化成固定长度的校验和/哈希码。

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Using these functions, we can convert and export our object structures and make data from our PHP database connections available to our Ajax applications using json_encode .

使用这些函数，我们可以转换和导出对象结构，还可以使用json_encode使来自PHP数据库连接的数据可用于Ajax应用程序。

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We also need methods to convert data to byte stream and byte stream to data, some of these functions are also provided in the CIOCPBuffer class.

l我们也需要字节流和数据相互转换的方法，在CIOCPBuffer类中提供了这些函数。

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