Variables can be local to a block : block scope variable « Language Basics « C++ Tutorial

1. C++ Tutorial
2. Language Basics
3. block scope variable

#include <iostream> 
using namespace std; 
 
int main() { 
  int x = 19; // x is known to all code. 
 
  if(x == 19) { 
    int y = 20; 
 
    cout << "x + y is " << x + y << "\n"; 
  } 
 
  // y not known here. 
 
  return 0; 
}

x + y is 39