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Closed 10 years ago.
Sorry for the noob question. This is my first day trying out Java programming. I need help retrieving the users input of which operator the user wants to use with integers.
import java.util.Scanner;
public class calculator {
public static void main (String args[]) {
Scanner number = new Scanner(System.in);
double num1,num2,answer;
char operator;
System.out.println("Enter first number: ");
num1 = number.nextDouble();
operator = number.nextChar(); /* the "nextChar" is not correct */
System.out.println("Enter second number: ");
num2 = number.nextDouble();
if (operator = '+'){
answer = num1 + num2; /* If statements do not work like this */
} /* I would use "else if", unsure if it allows */
if (operator = '-'){
answer = num1 - num2;
}
if (operator = '*'){
answer = num1 - num2;
}
if (operator = '/'){
answer = num1 / num2;
}
System.out.println(num1 + num2 + operator + answer);
}
}
Edited Version:
import java.util.Scanner;
public class calculator{
public static void main (String args[]) {
Scanner userInput = new Scanner(System.in);
String operator;
double num1,num2,answer = 0;
System.out.println("Enter first number: ");
num1 = userInput.nextDouble();
System.out.println("Enter operator: ");
operator = userInput.next();
System.out.println("Enter second number: ");
num2 = userInput.nextDouble();
if (operator.equals ("+")){
answer = num1 + num2;
}
else if (operator.equals ("-")){
answer = num1 - num2;
}
else if (operator.equals ("*")){
answer = num1 * num2;
}
else if (operator.equals ("/")){
answer = num1 / num2;
}
System.out.println("First number:" + num1);
System.out.println("Operator:" + operator);
System.out.println("Second number:" + num2);
System.out.println("Answer: " + answer);
}
}
First number:10.0
Operator:*
Second number:3.14
Answer: 31.400000000000002
Thanks a lot guys! Helped a lot!
Ok. This works and can help you on your road to java
public class Tester4 {
public static void main(String args[]) {
Scanner input = new Scanner(System.in);
double num1, num2, answer = 0;
String operator;
System.out.println("Enter first number: ");
num1 = input.nextDouble();
System.out.println("Enter operator: ");
operator = input.next();
System.out.println("Enter second number: ");
num2 = input.nextDouble();
if(operator.equals("+")) {
answer = num1 + num2;
} else if(operator.equals("-")) {
answer = num1 - num2;
} else if(operator.equals("*")) {
answer = num1 - num2;
} else if(operator.equals("/")) {
answer = num1 / num2;
}
System.out.println("First number:" + num1);
System.out.println("Operator:" + operator);
System.out.println("Second number:" + num2);
System.out.println("Answer: " + answer);
}
}
Use == in comparisons, not = (that means assignation).
As other have already pointed out, use the == operator to check for equality. The = operator will assign values instead.
In order to read a single character from the Scanner, take a look at the following question: Scanner method to get a char. There you'll find the suggestion to use Scanner.findInLine() method, which receives a regular expression as an argument. Providing the . wildcard character as pattern, you'll be able to get a String with the one next character, and using charAt(0) on it, you'll get it as a char.
Scanner sc = new Scanner("abc");
char ch = sc.findInLine(".").charAt(0);
System.out.println(ch); // prints "a"
Of course, you could also just use Scanner.next() to get the next word as a String, and just get its first character. But take into account that doing so would discard from the input buffer the rest of the word.
You need to use
if (operator == '+')
Notice the 'double equal to'.
Related
Am trying to write simple program to find average of 3 int values, but it always seems to get the average wrong
import java.util.Scanner;
public class IntegerAverage {
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
int num1;
int num2;
int num3;
// Ask user
System.out.println("Input 1st number");
num1 = in.nextInt();
System.out.println("Input 2nd number");
num2 = in.nextInt();
System.out.println("Input 3rd number");
num3 = in.nextInt();
// Print answer
System.out.println("The average is:"+ ((num1 + num1 + num3)/3));
}
}
Help is greatly appreciate
Besides having num1 twice and missing num2, as already mentioned above, you will always get integer-results only, e.g. for num1 = 1, num2 = 2 and num3 = 2 your code will plot 1 as result instead of 1.667. You might enforce double-results in your output by writing
System.out.println("The average is:"+ ((num1 + num2 + num3) / 3.0));
It's supposed to be:
import java.util.Scanner;
public class IntegerAverage {
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
int num1;
int num2;
int num3;
// Ask user
System.out.println("Input 1st number");
num1 = in.nextInt();
System.out.println("Input 2nd number");
num2 = in.nextInt();
System.out.println("Input 3rd number");
num3 = in.nextInt();
// Print answer
System.out.println("The average is:"+ ((num1 + num2 + num3)/3));
}
}
You accidentally added num1 twice, and forgot num2.
This question already has answers here:
Java printing a String containing an integer
(9 answers)
Closed 4 years ago.
I'm a beginner and I am trying to make a simple calculator in java. Everything works fine except for Addition has wrong output (e.g. 1+1 = 1.01.0). Here is a sample of my code
package Package;
import java.util.Scanner;
public class SimpleCalculator {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Enter Equation:");
double num1 = input.nextDouble();
String oper = input.next();
String plus, minus, divide, modulus, multiply;
plus = "+";
minus = "-";
divide = "/";
multiply = "*";
modulus = "%";
//Everything is the same but addition seems to have wrong output
if (oper.equals(plus))
{
double num2 = input.nextDouble();
System.out.println("= " + num1 + num2);
}
else if (oper.equals(minus))
{
double num2 = input.nextDouble();
System.out.println(num1 - num2);
You are printing the Strings num1 and num2, not the result of the calculation.
When you print out a string ("=" in your case), Java will treat any number added to it as Strings as well).
To solve this, just add your calculation into parentheses to allow Java to calculate them separately:
System.out.println("=" + (num1 + num2));
The code should output a table for Farenheit and Celsius
public static void main(String[] args) {
System.out.println("Fahrenheit\tCelsius");
System.out.println("=======================");
for(int temp = -45; temp <= 120; temp += 5) //for(int i = 0; i <= 100; i+= 10)
{
System.out.printf("%5d |", temp);
double sum = (temp + (9.0/5.0)) * 32;
System.out.printf("%5d", (int)sum );
System.out.println();
You need to add a do while() loop to continue with the questions, for example:
static Scanner input;
static Scanner scanner;
static String question;
public static void main(String[] args) {
do {
int number1 = (int) (Math.random() * 10);
int number2 = (int) (Math.random() * 10);
input = new Scanner(System.in);
System.out.print("What is " + number1 + " * " + number2 + "? ");
int answer = input.nextInt();
while ((number1 * number2) != answer) {
System.out.print("Incorrect. Please try again. What is "
+ number1 + " * " + number2 + "? ");
answer = input.nextInt();
}
if ((number1 * number2) == answer) {
System.out.println("Correct. Nice work!");
System.out.println("Want more questions yes or no? ");
scanner = new Scanner(System.in);
question = scanner.next();
}
} while (question.toLowerCase().equals("yes") ||
question.toLowerCase().equals("y"));
}
Simplest way would be do while loop. Example:
do{
// What you want to repeat and make sure to change have way to get out of loop like this:
System.out.print("Want more questions yes or no? ");
question = scanner.next();
}while(question.equals("yes") || question.equals("y"));
There's a few errors in your code but instead of giving you the entire solution to your homework problem I suggest you start with the simple case of reading input until the user enters 'n':
String input = "";
Scanner scanner = new Scanner(System. in);
while (!input.equals("n")) {
System.out.println("continue y/n?");
input = scanner.nextLine();
}
Add the generation of random ints, checking of answers etc inside the while loop body. Make sure to use equals instead of == when comparing two Strings
I'm fairly new to java, so don't think this is some idiot. Anyways, I've been trying to make a program that can read a certain letter from the console and then decide which operation to use, let's say to add. However, I can't get an If loop to read the variable that decides which operator to use, here is the code, and please help.
import java.util.Scanner;
class Main {
public static void main(String[] args) {
Scanner user_input = new Scanner( System.in );
int number;
String function;
System.out.println("What Do You Want to Do? (a to add; s to" +
" subrtact; d to divited; m to multiply, and sq to square your nummber.)" );
function = user_input.next();
if (function == "sq"){
System.out.print("Enter your number: ");
number = user_input.nextInt();
System.out.print(number * number);
} else {
System.out.println("Unidentified Function!");
}
}
}
(I made the description shorter so that it would fit).
This is just an example to get you started in the right direction.
import java.util.Scanner;
public class Example {
public static void main(String[] args) {
Scanner user_input = new Scanner(System.in);
int num1, num2, result;
System.out.println("What Do You Want to Do? (a to add; s to"
+ " subrtact; d to divited; m to multiply, and s to square your nummber.)");
String choice = user_input.next();
// Add
if (Character.isLetter('a')) {
System.out.println("Enter first number: ");
num1 = user_input.nextInt();
System.out.println("Enter second number: ");
num2 = user_input.nextInt();
result = num1 + num2;
System.out.println("Answer: " + result);
}
}
}
If you use hasNext() on a scanner it will wait for an input until you stop the program. Also using equals() is a better way of comparing strings.
while(user_input.hasNext()){
function = user_input.next();
if (function.equals("s")){
System.out.print("Enter your number: ");
number = user_input.nextInt();
System.out.print(number * number);
} else {
System.out.println("Unidentified Function!");
}
}
Scanner s = new Scanner(System.in);
String str = s.nextLine();
int a=s.nextInt();
int b=s.nextInt();
if(str.equals("+"))
c=a+b;
else if(str.equals("-"))
c=a-b;
else if(str.equals("/"))
c=a/b;
// you can add operators as your use
else
System.out.println("Unidentified operator" );
I hope it helps!
This question already has answers here:
Scanner is skipping nextLine() after using next() or nextFoo()?
(24 answers)
Closed 8 years ago.
I am trying to make a simple calculator which can add, substract, divide and multiply any two numbers.
The way it works is that I ask for a number, then I ask for a sign (+,-,*,/) , and then I ask for the second number. The math should be done accordingly afterwards.
However I can't get the 'math sign' to be recognized properly by the program.
Here is my code:
package practice1;
import java.util.Scanner;
public class maiin {
public static void main(String[] args){
System.out.println("it works.");
double num1;
double num2;
String sign;
double total;
System.out.println("Please enter a number: ");
Scanner input = new Scanner(System.in);
num1 = input.nextDouble();
System.out.println("Enter a +,-,/,* sign: ");
sign = input.nextLine();
input.nextLine();
System.out.println("Enter another number: ");
num2 = input.nextDouble();
if (sign.equals("+")){
total = num1 + num2;
System.out.println("Your total is: " + total);
} else if (sign.equals ("-")) {
total = num1 - num2;
System.out.println("Your total is: " + total);
} else if (sign.equals ("/")) {
total = num1 / num2;
System.out.println("Your total is: " + total);
} else if (sign.equals ("*")) {
total = num1 * num2;
System.out.println("Your total is: " + total);
} else {
System.out.println("Please enter the a proper sign");
}
When I run the program, I always get "Please enter the a proper sign".
Thank you in advanced.
I think you need to change
sign = input.nextLine();
input.nextLine();
to
sign = input.nextLine();
sign.nextLine();