How to make a simple calculator using HTML and Javascript?

Question

How to make a simple calculator using HTML and Javascript?

asked Feb 17, 2021 by Harsh (1.5k points)

I have a piece of code for making a Javascript calculator that is not working, is there any alternatives code for that or how do I fix the error?

showresult(choise){
var n1=parsefloat(document.getElementById('num1').value);
var n2=parsefloat(document.getElementById('num2').value);
var r;
var c=choise;

switch(c)
	{
	case '1':
		r=n1+n2;
		break;
	case '2':
		r=n1-n2;
		break;
	case '3':
		r=n1*n2;
		break;
	case '4': 
		r=n1/n2;
		break;
	case '5':
		r=n2*100/n1;
		break;
	default:
		break;
			
	}
document.getElementById('result').innerHTML=r;

	

}

<!DOCTYPE html>
<html>
<head>
<title>Calculator</title>
<script src="calculator.js" type="text/javascript"></script>
</head>
<body>


<h1>My calculator</h1>
<table border="1" cellpadding="5" cellspacing="5" width="600">
<tr align="center">
<td>First number</td>
<td>Second Number</td>
<td>Result</td>
</tr>
<tr align="center">
<td><input name="number1" type="text" size=10 id='num1'/></td>
<td><input name="number2" type="text" size=10 id='num2'/></td>
<td> <input type="text" id='result' readonly ></td>
</tr>
<tr>
<td colspan="3">
<button onclick="showresult('1')">+</button>
<button onclick="showresult('2')">-</button>
<button onclick="showresult('3')">*</button>
<button onclick="showresult('4')">/</button>
<button onclick="showresult('5')">%</button>
</td>
</tr>

</table>
</body>
</html>

1 Answer

Vikram Aadi · Answer 1 · 2021-04-28T07:22:15+0000

Java is a very high programming language. Because of the diversity java has, it's possible to build almost anything. Let’s make a simple calculator using java.

Using the Scanner class, take two numbers
- Switch case branching is used to execute the section
- To compare the corresponding operations, use a switch case
- To test the respective operations using a switch event

Code:
// Java program for simple calculator
import java.io.*; // importing necessary libraries
import java.lang.*; // importing necessary libraries
import java.lang.Math;
import java.util.Scanner;
public class BasicCalculator {
public static void main(String[] args)
{
// stores two numbers
double number1, number2;
// Taking input from the user
Scanner sc = new Scanner(System.in);
System.out.println("Please enter the numbers");
// take the inputs
number1 = sc.nextDouble();
number2 = sc.nextDouble();
System.out.println("Please enter the operator (+,-,*,/)");
char op = sc.next().charAt(0);
double o = 0;
switch (op) {
// Case to add two numbers
case '+':
o = num1 + num2;
break;
// Case to subtract two numbers
case '-':
o = num1 - num2;
break;
// Case to multiply two numbers
case '*':
o = num1 * num2;
break;
// Case to divide two numbers
case '/':
o = num1 / num2;
break;
default:
System.out.println("You enter wrong input");
break;
}
System.out.println("The final result:");
System.out.println();
// print the final result
System.out.println(num1 + " " + op + " " + num2+ " = " + o);
}
}

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How to make a simple calculator using HTML and Javascript?

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