Calculator program

[hebaa]

i want to make a java program (Netbeans) as a calculator that reads from the user 2 numbers and the user choose an operation from + - / * and the results appears with handling exceptions


Plzz reply me ASAP

Heba
Egypt
Thanksssssss

[Ganon11]

OK, that's very nice; what are you having trouble with? Have you started? Do you have errors you don't understand?

Please make an attempt to solve your own problem before coming to us with questions.

[hebaa]

OK, that's very nice; what are you having trouble with? Have you started? Do you have errors you don't understand?

Please make an attempt to solve your own problem before coming to us with questions.

Yes, I've started but i cant make the program read the 2nd number, the program just ends...


Would you help?


[CODE=java]package Assignments;

import java.io.Buffere dReader;
import java.io.IOExcep tion;
//import java.io.InputSt ream;
import java.io.InputSt reamReader;

public class Assignment1 {


public static int sum(int x , int y){
return x+y;}


public static int min(int x, int y){
return x-y;}


public static int multiply(int x, int y){
return x*y;}


public static int divide(int x, int y){
return x/y;}



public static void main(String[] args) throws Exception {


//try{

BufferedReader in = new BufferedReader( new InputStreamRead er(System.in));
//String s=in.readLine() ;
int num1=in.read();

if (num1==in.read( ))
System.out.prin tln("Enter a Number");
else {
System.out.prin tln("Choose an operation (* + - /)");
}

char oper = (char) in.read();
int num2=in.read();
if( (num2==in.read( ))&& (oper==(char)in .read())){
System.out.prin tln(num2); }
//System.out.prin tln(in.read());



}
//else
//System.out.prin tln("Choose a correct operation");


//switch(oper){
//case '+':
//System.out.prin tln(sum(num1,nu m2));break;
//case '-':
//System.out.prin tln(min(num1,nu m2));break;
//case '*':
//System.out.prin tln(multiply(nu m1,num2));break ;
//case '/':
//System.out.prin tln(divide(num1 ,num2));break;
//default:
//System.out.prin tln("Please Enter a valide operation");









//if(x!=0){

//}

//String ss=in.readLine( );
//if(ss!=null){

//String sss=in.readLine ();
//if(sss!=null){
//System.out.prin tln(s + ss + sss + " = ");
//System.out.prin tln(sum(s, sss));
//}




//}





//catch (Exception e) {
//System.out.prin tln("Error");
//System.out.prin tln();
//System.out.prin tln("This program is like a calculator for certain operations (+ - * /)");//
//}



}[/CODE]

[Ganon11]

Yes, I've started but i cant make the program read the 2nd number, the program just ends...


Would you help?


[CODE=java]public static void main(String[] args) throws Exception {


//try{

BufferedReader in = new BufferedReader( new InputStreamRead er(System.in));
//String s=in.readLine() ;
int num1=in.read();

if (num1==in.read( ))
System.out.prin tln("Enter a Number");
else {
System.out.prin tln("Choose an operation (* + - /)");
}

char oper = (char) in.read();
int num2=in.read();
if( (num2==in.read( ))&& (oper==(char)in .read())){
System.out.prin tln(num2); }
//System.out.prin tln(in.read());



}
}
[/CODE]

Let's take a look at just your main function. Do you know how to use a BufferedReader to get input? If so, you should know that the .read() function does not return an integer.

Not only that, but you are calling in.read() twice just for num1 - before you even output a prompt telling the user to enter a number!

You need to re-think this portion of your code. Write down, step-by-step, what you need to do. Only once you have this figured out should you go back to your code and try to fix this program.

[hsn]

you have to orgnize your way of entering the data that you need
and in JAVA an input will always read it as a string.
so you need to convert the input to a number.

GOOD LUCK
hsn

[hebaa]

I dont know how to convert from String to int to be able to use the methos od summation and ...the others.

String num1=in.readLin e();
when i try the casting always says; cannot convert from string to int

[hebaa]

switch(oper){
case '+':
System.out.prin tln(sum(num1,nu m2));break;
case '-':
System.out.prin tln(min(num1,nu m2));break;
case '*':
System.out.prin tln(multiply(nu m1,num2));break ;
case '/':
System.out.prin tln(divide(num1 ,num2));break;
default:
System.out.prin tln("Please Enter a valide operation");

if(s!=readLine( )){
System.out.prin tln("Enter a Number");
}




always says: cannot swtich on string

[JosAH]

I dont know how to convert from String to int to be able to use the methos od summation and ...the others.

String num1=in.readLin e();
when i try the casting always says; cannot convert from string to int

Note that a cast in Java never changes an object from one type to another type.
Read the API docs for the Integer or/and Double classes. You have to *convert*
your String line to an Integer or Double.

kind regards,

Jos

[hebaa]

I still dont know how to convert from string to int to be able to use a method that takes 2 int's as parameters.

public static int sum(int num1 , int num2){
return num1+num2;}


that's the method

in da main:
i tried:
String oper=in.readLin e();
String num2=in.readLin e();
System.out.prin tln("= ");

Integer.getInte ger(oper);
Integer.getInte ger(num1);
Integer.getInte ger(num2);
if( oper==""+"")
System.out.prin tln(sum(num1,nu m2));



dont know what to do .. please help

[hebaa]

I still dont know how to convert from string to int to be able to use a method that takes 2 int's as parameters.

public static int sum(int num1 , int num2){
return num1+num2;}


that's the method

in da main:
i tried:
String oper=in.readLin e();
String num2=in.readLin e();
System.out.prin tln("= ");

Integer.getInte ger(oper);
Integer.getInte ger(num1);
Integer.getInte ger(num2);
if( oper==""+"")
System.out.prin tln(sum(num1,nu m2));



dont know what to do .. please help

i've tried
int x = Integer.parseIn t(oper);

but it doesnt fix my problem

[Ganon11]

i've tried
int x = Integer.parseIn t(oper);

but it doesnt fix my problem

Well, it's not going to work for oper, because oper is supposed to be '+', '-', '*', or '/'. None of these are numbers! You want to use Integer.parseIn t on num1 and num2.

[hebaa]

String oper=in.readLin e();


if(oper!="+"||o per!="-"||oper!="*"||o per!="/")
System.out.prin tln("Please Enter a valid operation");

the condition does not work...
what to do?

[Ganon11]

Google String.java. Look at the very first result of that search. Look for a method calls equalsIgnoreCas e(). Use this instead of comparison operators.

[alexJavaRocks]

For the integer parsing problem, all you need to do is get the String, do

int answer = Integer.parseInt(answerString);

That should work. If it doesn't tell me and show me your code.

[hebaa]

Thank you everybody iam done with my code.

Heba :) thankssss