package string/** * 字符串转double */fun main(args: Array
    
     ) {    println(strToDouble("5.0"))    println(strToDouble(".0"))    println(strToDouble("1."))    println(strToDouble("1.556"))}fun strToDouble(str: String): Double {    var regex = Regex("[0-9]+(\\.[0-9]+){0,1}")//正则[0-9] 后面如果有就必须是 .[0-9]+或者没有    if (!regex.matches(str)) {        return 0.0    }    //先求最大位    var maxCarry = str.indexOf(".") - 1    var result = 0.0    var charArray = str.toCharArray()    //for循环cha数组,只要不是".", 就 值 * 10的carry次方    for (ch in charArray) {        if (ch != '.') {            result += Math.pow(10.0, maxCarry.toDouble()) * (ch - '0')            maxCarry--        }    }    return result}