Posted by: divdude July 18, 2007
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import java.util.Scanner;
import java.io.*;
public class quadraticEquation{
public static void main(String[] args){
Scanner Keyboard = new Scanner(System.in);
String inputString=args[0];
double[] values=parseInputString(inputString);
double a, b, c, discriminant, rootA, rootB;
a = values[0];
b = values[1];
c = values[2];
discriminant = (Math.pow(b, 2)) - (4*a*c);
if(discriminant == 0.0) {
rootA = (-b + Math.sqrt(discriminant)) / (2 *a);
System.out.println("There is one root and the value of the root is: " + rootA);
}
else {
if(discriminant > 0.0) {
rootA = (-b + Math.sqrt(discriminant)) / (2 * a);
rootB = (-b - Math.sqrt(discriminant)) / (2 * a);
System.out.println("There are two real roots and the value of the roots are:"+ rootA + rootB);
}
else {
if(discriminant < 0.0) {
rootA = (-b + Math.sqrt(-discriminant)) / (2 * a);
rootB = (-b + Math.sqrt(-discriminant)) / (2 * a);
System.out.println("There are two imaginary roots and the value of the roots are: " + rootA + rootB);
}
}
}
System.exit(0);
}
public static double[] parseInputString(String inputString){
double[] d=new double[3];
int sign=1;
int pos1=inputString.indexOf("x*2");
int pos2=inputString.length();
String a=inputString.substring(0,pos1);
d[0]=Double.parseDouble(a);
inputString=inputString.substring(pos1+3,pos2).trim();
if(inputString.charAt(0)=='-')
sign=-1;
else
sign=1;
pos1=inputString.indexOf("x");
String b=inputString.substring(1,pos1);
d[1]=Double.parseDouble(b)*sign;
pos2=inputString.length();
inputString=inputString.substring(pos1+1,pos2).trim();
if(inputString.charAt(0)=='-')
sign=-1;
else
sign=1;
pos2=inputString.length();
String c=inputString.substring(1,pos2);
d[2]=Double.parseDouble(c)*sign;
return d;
}
}
It is basically same program but it takes input in the form of ax*2+bx+c as a
command line parameter.
To run excecute , compile and run as
java quadraticEquation 2x*2-4x+1
and son on. you can have spaces as well if you like.