Objective

Implement a function that copies n bytes from src to dst and returns dst, producing the correct result even when the two regions overlap.

Steps

• Copy exactly n raw bytes from src to dst. Treat the data as bytes, not as a string: there is no terminator, and an embedded \0 must be copied like any other byte.
• The regions may overlap. If you copy front-to-back while dst sits ahead of src, you overwrite source bytes before reading them and corrupt the result. This is the whole difference from memcpy.
• When dst is greater than src, copy back-to-front (from the last byte to the first). Otherwise copy front-to-back.
• If n is 0, copy nothing and leave both buffers untouched.
• Always return dst.

Objective

Implement a function that copies n bytes from src to dst and returns dst, producing the correct result even when the two regions overlap.

Steps

• Copy exactly n raw bytes from src to dst. Treat the data as bytes, not as a string: there is no terminator, and an embedded \0 must be copied like any other byte.
• The regions may overlap. If you copy front-to-back while dst sits ahead of src, you overwrite source bytes before reading them and corrupt the result. This is the whole difference from memcpy.
• When dst is greater than src, copy back-to-front (from the last byte to the first). Otherwise copy front-to-back.
• If n is 0, copy nothing and leave both buffers untouched.
• Always return dst.