CODEWITHSUNDEEP
kotlin
user8199688
user8199688

Reputation: 53

Can an integer in Kotlin be equal to an math expression?

I am making a program that solves a math expression, for example, 2+2. Can I set an integer equal to something like this:

val input = "2+2"
input.toInt()

Upvotes: 1

Views: 3465

Answers (5)

Ambuj Mishra
Ambuj Mishra

Reputation: 21

No you cannot convert directly a String Mathematical Expression to Integer.

But you can try following approach to convert String Mathematical Expression to Integer ->>

    var exp: String = "2+3-1*6/4"
    var num: String = ""
    var symbol: Char = '+'
    var result: Int = 0

    for(i in exp)
    {
        if(i in '0'..'9')
            num += i
        else
        {
            if(symbol == '+')
                result += Integer.parseInt(num)
            else if(symbol == '-')
                result -= Integer.parseInt(num)
            else if(symbol == '*')
                result *= Integer.parseInt(num)
            else if(symbol == '/')
                result /= Integer.parseInt(num)

            num=""
            symbol = i
        }
    }

    //To calculate the divide by 4 ( result/4 ) in this case
    if(symbol == '+')
        result += Integer.parseInt(num)
    else if(symbol == '-')
        result -= Integer.parseInt(num)
    else if(symbol == '*')
        result *= Integer.parseInt(num)
    else if(symbol == '/')
        result /= Integer.parseInt(num)

    println("result is $result") //Output=> result is 6
}

Upvotes: 2

guenhter
guenhter

Reputation: 12177

This can be done with the kotlin script engine. For details see Dynamically evaluating templated Strings in Kotlin

But in a nutshell it's like this:

val engine = ScriptEngineManager().getEngineByExtension("kts")!!
engine.eval("val x = 3")
val res = engine.eval("x + 2")
Assert.assertEquals(5, res)

Upvotes: 1

Hammad Tariq
Hammad Tariq

Reputation: 13471

No, Integer cannot be equal to math expression.

You may use String Templates

Strings may contain template expressions, i.e. pieces of code that are evaluated and whose results are concatenated into the string.

A template expression starts with a dollar sign ($) and consists of either a simple name:

  val i = 10
  val s = "i = $i" // evaluates to "i = 10"

Upvotes: -2

Kemal Turk
Kemal Turk

Reputation: 2308

No you can't.

You can like this:

val a = "2"
val b = "2"
val c = a.toInt() + b.toInt()

Or

val input = "2+2"
val s = input.split("+")
val result = s[0].toInt() + s[1].toInt()

Upvotes: 1

zsmb13
zsmb13

Reputation: 89668

Kotlin doesn't have any built in ways for evaluating arbitrary expressions. The toInt function can only parse a String containing a single whole number (it's just a wrapper for Integer.parseInt).

If you need this functionality, you'll have to parse and evaluate the expression yourself. This problem is no different than having to do it in Java, for which you can find discussion and multiple solutions (including hacks, code samples, and libraries) here.

Upvotes: 7

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