#include <stdio.h>
#include <math.h>
int main()
/* 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! */
{
    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 */
  scanf("%f", &onevar);
  while(onevar >=0 ) {   /*只要onevar大於或等於零我們就一直重複做{...} */
     ans=sqrt(onevar);  /*其實sqrt的參數也應該為double 型別*/
     printf(" SQRT(%f)=%f\n", onevar, ans);
     printf("X=? ");  scanf("%f", &onevar);
  } /* while(onevar */
  return 0;
}