#include "math.h"
main()
{
float x1=1.0,x2,a;
printf("please input a ");
scanf("%f",&a);

do
{x2=0.5*(x1+(a/x1));
x1=x2;
}while(fabs(x2-x1)>=1e-5);
printf("aqrt(a)= %10.4f",x2);
}

输出结果不正确

#include "math.h"
main()
{
float x1,x2,a;
printf("please input a ");
scanf("%f",&a);
x1=1.0;
do
{
x1=x2;
x2=0.5*(x1+(a/x1));

}while(fabs(x2-x1)>=1e-5);
printf("aqrt(a)= %10.4f",x2);
}

把迭代的顺序弄错了，使得x1=x2, fabs(x1-x2)=0了，只执行一次就结束了
真是晕了！！