Memory Allocation in C and Java

This is an extremely basic question, and it seems to me that you need to learn a lot more about programming before you are ready for a freelance project.

C and Java are completely different languages, both in concept and in use. C is a compiled language, most Java implementations are interpreted code at run time or use a just-in-time byte code compiler.

C is a functional programming language, based on data structures, pointers, and function calls. In C, you must allocate and manage memory using the low level calls malloc, calloc, realloc, free, etc. If every call to allocate memory is not matched with a call to free it, you will have a memory leak. If you try to use a pointer to memory before you allocate it or after you free it, your program will crash. C has no protection to ensure that you do not access memory beyond the end of an array or overwrite memory that is being used by some other data structure.

Java is an object-oriented language. You can use it for functional programming, but most Java programs are based on using object classes and their methods. Objects communicate with each other by calling each other's methods. Variables that store data for instances of objects are hidden inside the objects and can only be accessed through member functions. Java implements a system of "garbage collection" for object instances. If the memory management system sees that an object is no longer being used (referenced) by any other object, then it is removed and put into the garbage. When garbage collection occurs, the memory used by that object instance is recovered and can be used for allocating another object instance.

For you, the choice of which language you use depends on the nature of your project. If you have no experience at all, I don't think you should use either of them, but instead use a language like Python, which is much more friendly to beginners.