Making a power with an double base and an integer exponent without any math. library in Java

Question

I need to make a power of a double base with an integer exponent without using any math. library but I get the error:

package potencia;

import java.util.Scanner;

public class Potencia {
int n=0;
double b=0,p=0, potencia=1;
Scanner entrada= new Scanner(System.in);

public static void main(String[] args) {
    int n=0;
    double b=0,p=0, potencia=1;
    Scanner entrada= new Scanner(System.in);

    System.out.println("Por favor ingrese la base de su potencia: ");
    b=entrada.nextDouble();

    System.out.println("Por favor ingrese el exponente de su     potencia");
    n=entrada.nextInt();
    for (int i=0; i<n; i++){
        potencia= potencia*b;
        }
    System.out.println("La potencia "+n+" de "+b+ " es: "+potencia);  

    }

Error:

Exception in thread "main" java.util.InputMismatchException at java.util.Scanner.throwFor(Scanner.java:864) at java.util.Scanner.next(Scanner.java:1485) at java.util.Scanner.nextFloat(Scanner.java:2345) at potencia.Potencia.main(Potencia.java:20) Java returned: 1

Why are you declaring variables twice? Also I don't get any errors. What input were you giving? — Yoshikage Kira, Sep 11 '19 at 03:17
Oh, I was doing it in different classes so I tried copying and pasting everything in the same one but I already removed them from the outside. — Alejandro Mejía, Sep 11 '19 at 03:41
Still works. I think you mean exponent. Which will give error since scanner is reading int. — Yoshikage Kira, Sep 11 '19 at 03:45
Are you copying it? Maybe I'm missing a library and what I need is a power as (5.2)^2 but I get an error when I put the base 5.2. — Alejandro Mejía, Sep 11 '19 at 03:50
Ths is not a [tag:compiler-error], and it has nothing to do with exponentiation. Have you considered looking up the exception in the Javadoc? Obviously you typed in something wrong. — user207421, Sep 11 '19 at 06:51

score 0 · Answer 1 · answered Sep 11 '19 at 03:57

I have removed redundant deceleration. Besides that everything is same.

package potencia;

import java.util.Scanner;

public class Potencia {

    public static void main(String[] args) {
        int n = 0;
        double b = 0, p = 0, potencia = 1;
        Scanner entrada = new Scanner(System.in);

        System.out.println("Por favor ingrese la base de su potencia: ");
        b = entrada.nextDouble();

        System.out.println("Por favor ingrese el exponente de su     potencia");
        n = entrada.nextInt();
        for (int i = 0; i < n; i++) {
            potencia = potencia * b;
        }
        System.out.println("La potencia " + n + " de " + b + " es: " + potencia);

    }

}

Output:

Por favor ingrese la base de su potencia: 
5.2
Por favor ingrese el exponente de su     potencia
2
La potencia 2 de 5.2 es: 27.040000000000003

o_o what IDE do you use? I have netbeans and I just copied the code and it's the same. — Alejandro Mejía, Sep 11 '19 at 04:00
@AlejandroMejía I am using Eclipse IDE. I don't know if it is IDE fault. You can test your code here. [JDoodle](https://www.jdoodle.com/online-java-compiler/) — Yoshikage Kira, Sep 11 '19 at 04:12

Making a power with an double base and an integer exponent without any math. library in Java

1 Answers1