# Kotlin 程序：將二進制數轉換為十進制，反之亦然 > 原文： [https://www.programiz.com/kotlin-programming/examples/binary-decimal-convert](https://www.programiz.com/kotlin-programming/examples/binary-decimal-convert) #### 在此程序中，您將學習使用 Kotlin 中的函數將二進制數轉換為十進制數，反之亦然。 訪問此頁面以了解[如何將二進制數轉換為十進制](http://www.wikihow.com/Convert-from-Binary-to-Decimal "Binary number to Decimal")。 ## 示例 1：將二進制數轉換為十進制的程序 ```kt fun main(args: Array<String>) { val num: Long = 110110111 val decimal = convertBinaryToDecimal(num) println("$num in binary = $decimal in decimal") } fun convertBinaryToDecimal(num: Long): Int { var num = num var decimalNumber = 0 var i = 0 var remainder: Long while (num.toInt() != 0) { remainder = num % 10 num /= 10 decimalNumber += (remainder * Math.pow(2.0, i.toDouble())).toInt() ++i } return decimalNumber } ``` **輸出** ```kt 110110111 in binary = 439 in decimal ``` * * * 訪問此頁面以了解[如何將十進制數轉換為二進制](http://www.wikihow.com/Convert-from-Decimal-to-Binary "Binary number to Decimal")。 ## 示例 2：將十進制數轉換為二進制的程序 我們可以使用`Integer.toBinaryString()`方法將十進制數轉換為二進制數。 ```kt fun main(args: Array<String>) { val num = 19 // converting decimal to binary val binary = Integer.toBinaryString(num) println("$num in decimal = $binary in binary") } ``` * * * 這是將十進制數字手動轉換為二進制的源代碼。 ## 示例 3：手動將十進制數轉換為二進制 ```kt fun main(args: Array<String>) { val num = 19 val binary = convertDecimalToBinary(num) println("$num in decimal = $binary in binary") } fun convertDecimalToBinary(n: Int): Long { var n = n var binaryNumber: Long = 0 var remainder: Int var i = 1 var step = 1 while (n != 0) { remainder = n % 2 System.out.printf("Step %d: %d/2, Remainder = %d, Quotient = %d\n", step++, n, remainder, n / 2) n /= 2 binaryNumber += (remainder * i).toLong() i *= 10 } return binaryNumber } ``` 運行該程序時，輸出為： ```kt Step 1: 19/2, Remainder = 1, Quotient = 9 Step 2: 9/2, Remainder = 1, Quotient = 4 Step 3: 4/2, Remainder = 0, Quotient = 2 Step 4: 2/2, Remainder = 0, Quotient = 1 Step 5: 1/2, Remainder = 1, Quotient = 0 19 in decimal = 10011 in binary ``` 以下是等效的 Java 代碼： [Java 程序：將二進制轉換為十進制，反之亦然](/java-programming/examples/binary-decimal-convert "How to convert binary to decimal and vice-versa in Java")