Kotlin:如何从二进制转换为十进制

fun binaryToDecimal(binaryString: String): Int {
    return binaryString.toInt(2)
}

fun main() {
    val binaryString = "1101"
    val decimalNumber = binaryToDecimal(binaryString)
    println("Binary $binaryString in decimal is $decimalNumber")
}

fun binaryToDecimalManual(binaryString: String): Int {
    var decimalNumber = 0
    for (i in binaryString.length - 1 downTo 0) {
        if (binaryString[i] == '1') {
            decimalNumber += Math.pow(2.0, (binaryString.length - 1 - i).toDouble()).toInt()
        }
    }
    return decimalNumber
}

fun main() {
    val binaryString = "1101"
    val decimalNumber = binaryToDecimalManual(binaryString)
    println("Binary $binaryString in decimal is $decimalNumber")
}

import java.math.BigInteger

fun binaryToDecimalBigInt(binaryString: String): BigInteger {
    return BigInteger(binaryString, 2)
}

fun main() {
    val binaryString = "1101"
    val decimalNumber = binaryToDecimalBigInt(binaryString)
    println("Binary $binaryString in decimal is $decimalNumber")
}

fun isValidBinaryString(binaryString: String): Boolean {
    return binaryString.matches(Regex("[01]+"))
}

fun main() {
    val binaryString = "1101a"
    if (isValidBinaryString(binaryString)) {
        val decimalNumber = binaryToDecimal(binaryString)
        println("Binary $binaryString in decimal is $decimalNumber")
    } else {
        println("Invalid binary string")
    }
}