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25. How does free() know how much memory to release? There’s no standard way. It can vary from compiler to compiler, even from version to version of the same compiler. free(), malloc(), calloc(), and realloc() are functions; as long as…
Read More23. What is a “null pointer assignment” error? What are bus errors, memory faults, and core dumps? These are all serious errors, symptoms of a wild pointer or subscript. Null pointer assignment is a message you might get when an…
Read More21. What happens if you free a pointer twice? If you free a pointer, use it to allocate memory again, and free it again, of course it’s safe If you free a pointer, the memory you freed might be reallocated.…
Read More19. What is the stack? A “stack trace” is a list of which functions have been called, based on this information. When you start using a debugger, one of the first things you should learn is how to get a…
Read More17. What is the difference between far and near ? Compilers for PC compatibles use two types of pointers. near pointers are 16 bits long and can address a 64KB range. far pointers are 32 bits long and can address…
Read More15. Is it better to use malloc() or calloc()? Both the malloc() and the calloc() functions are used to allocate dynamic memory. Each operates slightly different from the other. malloc() takes a size and returns a pointer to a chunk…
Read More13. When would you use a pointer to a function? Pointers to functions are interesting when you pass them to other functions. A function that takes function pointers says, in effect, “Part of what I do can be customized. Give…
Read More9. Is NULL always equal to 0(zero)? The answer depends on what you mean by “equal to.” If you mean “compares equal to,” such as if ( /* … */ ) { p = NULL; } (62)
Read More7. Can you subtract pointers from each other? Why would you? If you have two pointers into the same array, you can subtract them. The answer is the number of elements between the two elements. (63)
Read More5. What is a void pointer? A void pointer is a C convention for “a raw address.” The compiler has no idea what type of object a voidpointer “really points to.” If you write (83)
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