code天天写代码重新出发

//Prime Number Test
public class Test{   
    public static void Main(){
        try{
            PrintPrime(100,400);
        }catch(System.Exception ex){
            System.Console.WriteLine(ex.Message);
        }
    }
    //print prime number between low and High
    static void PrintPrime(int low, int high){
        string strErrMsg = "";
        if(low < 0 || high< 0){       
            strErrMsg = "Natural number must be 1+ integer!";
            throw new System.ArgumentOutOfRangeException("",strErrMsg);
        }
        if(high > int.MaxValue || low < int.MinValue){           
            strErrMsg = "Integer Value is out of range !";
            throw new System.ArgumentOutOfRangeException("",strErrMsg);
        }
        int ix = low;
        for (;ix <= high; ix++){
            if(IsPrime(ix)){
                System.Console.Write(ix + "\t");
            }
        }
    }
    // Is it a prime number     
    // returns : ture, is prime number
    //         : false,is not prime number       
    static bool IsPrime(int n){
        bool blnReturn = true;
        if (n <= 1){
            blnReturn = false;
        }
        for(int i=2; i<Sqrt(n); i++){
            if ( n % i == 0){
                blnReturn = false;
                break;
            }
        }
        return blnReturn;
    }
    //my Sqrt
    static double Sqrt(double num ){
        double E = 0.0000001f;
        double d = num /2;
        while (Abs(num - d * d) > E){
           d = (d + num / d) / 2;
        }
        return d;
    }    
    //my Abs
    static double Abs(double d){
        if ( d >= 0) {
            return d;
        }
        else{
            return -d;
        }
    }
}