What is the purpose of anonymous { } blocks in C style languages?

Question

What is the purpose of anonymous { } blocks in C style languages (C, C++, C#)

Example -

void function()
{

  {
    int i = 0;
    i = i + 1;
  }

          


        

Answer 1

One thing to mention is that scope is a compiler controlled phenomenon. Even though the variables go out of scope (and the compiler will call any destructors; POD types are optimised immediately into the code), they are left on the stack and any new variables defined in the parent scope do not overwrite them on gcc or clang (even when compiling with -Ofast). Except it is undefined behaviour to access them via address because the variables have conceptually gone out of scope at the compiler level -- the compiler will stop you accessing them by their identifiers.

#include 
int main(void) {
  int* c;
  {
    int b = 5; 
    c=&b;
  }
  printf("%d", *c); //undefined behaviour but prints 5 for reasons stated above
  printf("%d", b); //compiler error, out of scope
  return 0;
}

Also, for, if and else all precede anonymous blocks aka. compound statements, which either execute one block or the other block based on a condition.