convert static_castmalloc/free to new/delete

by

Just do

char* only_valid_data = new char[data_size];

to allocate.

To free you do

delete[] only_valid_data;

Important note: When you allocate memory with new it will allocate data_size elements, not data_size bytes (like malloc does). The size of an element is the size of the non-pointer base type, in your case e.g. sizeof(*only_valid_data). In this case the element size and the byte size is the same (as sizeof(char) is specified to always be 1), but if the base type is something else it will make a big difference.

For example, if you do

int* int_ptr = new int[10];

then ten integers will be allocated, not ten bytes. This is equivalent to

int* int_ptr = reinterpret_cast<int*>(malloc(10 * sizeof(*int_ptr)));

Also note that for complex types, like structures and classes, allocating with new (or new[]) does more than just allocating memory, it will also make sure that the allocated object(s) constructor is called. The malloc function only allocates memory, it doesn’t call the constructor.

Final note: The problem you have with the segmentation fault is probably not caused by your allocation, no matter how you allocate the memory. The problem is more likely because of something else, something you do not show in your question, like writing out of bounds of the allocated memory or dereferencing a null-pointer.

You need run your program in a debugger to catch the crash in action, it will allow you to examine the function call stack, and if the crash doesn’t happen in your code then you walk up the call stack until you reach your code. There you can examine the values of variables, to help you understand why the problem occurred.

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