What happens to memory after free()?

Question

I know that on you hard drive, if you delete a file, the data is not (instantly) gone. The data is still there until it is overwritten. I was wondering if a similar concept

Answer 1

Generally, it does stay around, unless you explicitly overwrite the string before freeing it (like people sometimes do with passwords). Some library implementations automatically overwrite deallocated memory to catch accesses to it, but that is not done in release mode.