When win32 program debugging, malloc to allocate memory, when the last free release memory error, the original code is as follows:
Here, after calling malloc memory allocation finished, pstr first address to 0x00c5abb0, copy this address to the memory window, track memory, as follows:
pstr assigned byte size is 32 bytes, where 32 bytes are not initialized set 0xcd, 4 th 0xfd behind Microsoft C ++ debugging stack with the value of the flag "no man's land" sentry position, where I understood to be used to identify the boundaries of memory, refer to the information in this article:
http://blog.sina.com.cn/s/blog_95bf1ccc010154uu.html
Then, after commissioning the next step, after _stprintf_s function runs, we discovered the problem:
Here, the red represents the memory changes, 0xfd has also been changed to 0xfe, memory that is out of line; a closer look at the formatted data is written _stprintf_s function strings in Unicode version of the prototype is _swprintf_s, in MSDN on, the unit of the second parameter is the number of characters instead of bytes:
After the clear problem, modify the second parameter passed to _stprintf_s maximum number of characters, as follows:
