[Textual Research] the principle of "hot and hot" and "Hot and thin copy"

On the programmer's website, I often see a paragraph (full of tears)

Hand-held two copy, mouth burst hot.

Explain why these two items are not equal to =:

Garbled Chunk:

This is due to the conversion problem between the GBK character set and the Unicode Character Set. There must be some characters in the conversion process of Unicode and the old encoding system, which cannot be expressed by Unicode. Unicode officially uses a placeholder to represent these words, which is: U + fffd replacement character. Then the U + fffd UTF-8 code out, exactly is '\ XeF \ xbf \ xbd '. If '\ XeF \ xbf \ xbd' is repeated multiple times, for example, '\ XeF \ xbf \ xbd ', then, if it is displayed in the GBK/cp936/gb2312/gb18030 environment, a Chinese character contains two bytes, and the final result is: Weight-weight (0 xefbf), kg (0 xbdef ), copy (0 xbfbd ).

Hot and hot garbled code:

On Windows, the MS Compiler (that is, the one with VC) in debug mode fills all uninitialized stack memory into 0xcc, in the string, the heap memory is filled with 0xcd. In the string, the heap memory is changed to 0xcd ". That is to say, there is hot and hot. Check the initialization...