I'm a student and i just studied the malloc, realloc, free, memset functions but i didn't understand WHY I SHOULD USE THEM!!! Since now i didn't use them and programs run. Please tell me!!
You do not have to use them if you do not need to. It is just a tool for a job which is nice to have and know when you need it.
You do not have to insert them in each program, as you are fine without having all four kinds of loops, conditional statement, switch statement, goto statement, variaditic functions, SFINAE, multithreading, singletones, lambdas, function objects, SFINAE, RTTI, virtual inheritance and other stuff in it.