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A similar situation arises when realloc() is supplied a pointer to nondynamically allocated memory. The realloc() function is used to resize a block of dynamic memory. If realloc() is supplied a pointer to memory not allocated by a memory allocation function, such as malloc(), the program may terminate abnormally.
This rule does not apply to null pointers. The standard officially declares that when given a null pointer, free() does nothing.
Noncompliant Code Example
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