exponent loop w/out math .pow.

[lillie field]

im trying to make a calculator without using math.pow. im writing my class and i seem to be stuck. here's my code.

public static int getRaiseToThePowerOf(int rpo, int n1, int n2)
{
rpo = 1;

if (n2 < 0)
{
System.out.println("Error: Exponent Must Be >=0");

}

else if (n2 == 0)
{
rpo = 1;
}

else if (n2 == 1)
{
rpo = n1;
}

else
{
return n1 * rpo(n1, n2-1);
}

when i try to compile i get an error saying that the compiler can't find symbol for "rpo" in the line "return n1 * rpo(n1, n2-1);". should i rename all "rpo" to "getRaiseToThePowerOf"? i'm stuck. please help.

[Muhammad Saifuddin]

compiler can't find symbol for  "rpo" in the line "return n1 * rpo(n1, n2-1);". 

because compiler consider "rpo" as method. which is not exist actually.

should i rename all "rpo" to "getRaiseToThePowerOf"? i'm stuck. please help.

Yes, but you need to provide three parameter to getRaiseToThePowerOf method,

see your method signature.

public static int getRaiseToThePowerOf(int rpo, int n1, int n2)

[marc weber]

Originally posted by lillie field:
...

public static int getRaiseToThePowerOf(int rpo, int n1, int n2)
   {     
        rpo = 1;
...

Welcome to JavaRanch!

Note that regardless of what you pass to the method as "rpo," that value is lost, because "rpo" is immediately reassigned to 1.
[ April 05, 2008: Message edited by: marc weber ]

[Rob Spoor]

Correct. Another problem is that you have paths that will return nothing. Observe:

public static int getRaiseToThePowerOf(int rpo, int n1, int n2)
{ 
    rpo = 1;
 
    if (n2 < 0) 
    {
        System.out.println("Error: Exponent Must Be >=0");
        // no return
    }
    else if (n2 == 0) 
    {
        rpo = 1;
        // no return
    }
    else if (n2 == 1) 
    {
        rpo = n1;
        // no return
    }
    else 
    {
        return n1 * rpo(n1, n2-1);
    }
}

Also, just printing something is not a good idea. Here's a small improvement:

public static int getRaiseToThePowerOf(int n1, int n2)
{ 
    int rpo = 1;
 
    if (n2 < 0) 
    {
        // throw an exception because something is wrong
        // document this exception!
        // return is not needed
        throw new IllegalArgumentException("Error: Exponent Must Be >=0");
    }
    if (n2 == 0) 
    {
        rpo = 1;
    }
    else if (n2 == 1) 
    {
        rpo = n1;
    }
    else 
    {
        rpo = n1 * getRaiseToThePowerOf(n1, n2 - 1);
    }
    // single return at the end
    return rpo;
}

[ April 06, 2008: Message edited by: Rob Prime ]

[lillie field]

thanks so much for your help!