What happens if I try to access memory beyond a malloc()'d region?

Question

I\'ve allocated a chuck of memory with char* memoryChunk = malloc ( 80* sizeof(char) + 1); What is keeping me from writing into the memory location beyond 81 un

Answer 1

Nothing is stopping you from doing that. If you do so, anything could happen: the program could continue on its merry way as if nothing happened, it might crash now, it might crash later, it might even erase your hard drive. This is the realm of undefined behavior.

There are a number of tools that try to detect or mitigate these types of problems, but nothing is fool-proof. One such tool is valgrind. valgrind watches your program's pattern of memory accesses and notifies you of problems like this. It does this by running your program in a virtual machine of sorts, so it hurts the performance of your program significantly, but it can help you catch lots of errors when used correctly.