What is memory overlapping in memcpy?
memcpy() leads to problems when source and destination addresses overlap as memcpy() simply copies data one by one from one location to another. For example consider below program.
How would you implement memcpy?
Implementation of memcpy is not a big deal, you need to typecast the given source and destination address to char* (1 byte). After the typecasting copy the data from the source to destination one by one until n (given length).
Does Memmove free memory?
memmove has nothing to do with clearing the old memory, and in fact in the only situations where you would want to use memmove , clearing the old memory would destroy the data you just copied! That’s because memmove is only useful when you expect the source and destination ranges to overlap.
Why is memcpy so slow?
I also had some code that I really needed to speed up, and memcpy is slow because it has too many unnecessary checks. For example, it checks to see if the destination and source memory blocks overlap and if it should start copying from the back of the block rather than the front.
What’s the difference between memcpy and memmove for overlapping memory?
memmove can handle overlapping memory, memcpy can’t. Obviously the source and destination now overlap, we’re overwriting “-bar” with “bar”. It’s undefined behavior using memcpy if the source and destination overlap so in this case cases we need memmove.
What is the behavior of the memcpy function?
The memcpy function copies n characters from the source object to the destination object. If the source and destination objects overlap, the behavior of memcpy is undefined.
Is there a way to create your own memcpy?
You can create own memcpy using a simplest memory-transfer algorithm just reads one byte at a time and writes that byte before reading the next. You can call this algorithm byte-by-byte. This algorithm is easy to implement but may not offer optimal performance, particularly if your memory bus is wider than 8 bits.
Do you need to include header file before using memcpy?
The memcpy function copies n characters from the source object to the destination object. If copying takes place between objects that overlap, the behavior is undefined. You need to include header file before using the memcpy function.