How are variables involved in a for loop's body if they are not defined?

Please help! I'm confused what value the variable result gets to multiply base by. By the way, I'm a beginner at java. I have to write a program for exponents that raises a base to a power WITHOUT USING Math.pow. Also, I'm having trouble with my if statement because it doesn't work. (When I remove the if statement everything works, but I don't understand how it works...) For the if statement, I want it so if the user types in 0 as the power then it displays the base.

 public static int exponent(int result) // defining method for raising base to power

   {

   int base; // defiing user input variables
   int power;
 {
Scanner reader = new Scanner(System.in); // scanner is called reader

System.out.println("Please enter the base."); // first input is base
base = reader.nextInt();

System.out.println("Please enter the exponent."); // second input  
power = reader.nextInt();
for (int i = 1; i <= power; i++) {
  result = base * result;
  System.out.println("Result: " + base + " ^ " + power + " = " + result);

  return 0;
  {

if (power == 0)
 System.out.println("Result: " + base);
 }
return power;
}