public class p3 {
  /* This program can find square root of any number that >=0
       and will stop when you enter a value that < 0 
       阿版權是蔡文能的, 歡迎拷貝分享初學者! */
  public static void main(String p[ ])  throws java.io.IOException
  {
     float onevar;   /* 變數名稱隨便我取的啦 */
     double ans;     /* 用來放答案 */
     printf("Find square root of X. Negative value will cease the program\n");
     printf("X=? ");   /* 還是問"X=?" 比較簡潔有力, 不用說onevar */
     onevar = (float) readDouble( );
     while(onevar >=0 ) {   /*只要onevar大於或等於零我們就一直重複做{...} */
        ans = Math.sqrt(onevar);  /*其實sqrt的參數也應該為double 型別*/
        ans = ((int)(ans*1000+0.5))/1000.0;
        printf(" SQRT(" + onevar  + ")=" + ans+ "\n");
        printf("X=? ");
        onevar =  (float)readDouble( );
     } /* while(onevar */
  } // main
  static void printf(String s) { System.out.print(s); }
  static float readDouble( ) throws java.io.IOException {
     java.io.InputStreamReader isr = new java.io.InputStreamReader(System.in);
     java.io.BufferedReader br = new java.io.BufferedReader(isr);
     return (float)Double.parseDouble( br.readLine( ) );
  } // readDouble
}