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);