Questions

Adenosine triphosphate (ATP) is a nucleotide which is also called as nucleoside triphosphate is a small molecule used in cells as a coenzyme. It is often referred to as the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism. Most of the cellular functions need energy in order to be carried out such as synthesis of proteins, synthesis of membranes, movement of the cell, cellular division, transport of various solutes etc. The ATP is the molecule that carries energy to the place where the energy is needed. When ATP breaks into ADP (adenosine diphosphate) and P_i (phosphate), the breakdown of the last covalent link of phosphate liberates energy that is used in reactions where it is needed.

Quality of transmission is governed both by nature of signal and nature of communication channel/medium.

ptr pointer is constant. In ptr = yourbuf the program is trying to modify it, hence an error.