C++ Tutorial/Function/function scope variables

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A local variable is initialized each time its block is entered

#include <iostream> 
using namespace std; 
 
void f(); 
 
int main() 
{ 
   
  for(int i=0; i < 3; i++) f(); 
   
  return 0; 
} 
 
// num is initialized each time f() is called. 
void f() 
{ 
  int num = 99; 
 
  cout << num << "\n"; 
 
  num++; // this has no lasting effect 
}
99
99
99

Function level variable

#include <iostream> 
using namespace std; 
 
void f1(); 
 
int main() 
{ 
  int val = 10; 
 
  cout << "val in main(): " << val << "\n"; 
  f1(); 
  cout << "val in main(): " << val << "\n"; 
 
  return 0; 
} 
 
void f1() 
{ 
  int val = 88; 
 
  cout << "val in f1(): " << val << "\n"; 
}
val in main(): 10
val in f1(): 88
val in main(): 10