/**
 * This files reviews functions and introduces variable scope.
 *
 */

// A global variable is accessible throughout your program.
int global_var;

void main(){
    global_var = 4;
    f1();
    
    // What will happen if we uncomment the line below
    // and try to print the value of local_var1?
    // printf("local_var1 %d\n", local_var1);
    
    global_var = f4(global_var);
    printf("global_var %d\n", global_var);
}

void f1(){
    int local_var1 = 23;  // accessible from this function only
    local_var1 = global_var;
    printf("local_var1 %d\n", local_var1);
    f2();
    f3(12);
}

void f2(){
    int local_var2 = 92;  // accessible from this function only
    
    // Is the statement below, if uncommented, valid and correct?
    //local_var2 = local_var1;
    
    printf("local_var2 %d\n", local_var2);
}

void f3(int local_var1){
    printf("local_var1 %d\n", local_var1);
}

// What does function f3 do?
int f4(int x){
    x = x * 2;
    return x;
}