5/21 TIL: C/C++ setup on MacOS & C pointers

To run C programs, we need a compiler

• clang and gcc are usually used on MacOS—they are built-in
• we can check if these compilers exist in our system by doing this on terminal:

  gcc -v

  clang -v

• if they aren't found, we can install it by running: xcode-select --install
• https://www.youtube.com/watch?v=f0vVV4NPmjQ

To run a C program in VS code

• Install the 'C/C++' and 'code runner' extensions
• Write your C program and compile it by selecting Terminal > Run Build Task (choose gcc/clang build in the dropdown)

Pointers in C

• https://www.cs.fsu.edu/~myers/c++/notes/pointers1.html
• int *p, int* p are the same
• asterisk (*) used in the declaration statement is used to define the pointer variable
• asterisk (*) used elsewhere is used to dereference the pointer; for instance:

  int x = 10;

  // * used here in the declaration statement has nothing to do with dereferencing; we are simply declaring a variable named aptr of type 'pointer to int' (meaning it stores the address of an integer variable)

  int *aptr = &x; 

  printf("%x returns a memory address", aptr);

  // * here is now used for dereferencing

  printf("%d is the value dereferenced, *aptr);