#include <stdio.h>
main ()
{
 float a, b_b, t_c1, t_c2, c_l, b;
while (a != 0)
{
printf ("enter account number:");
 scanf ("%f",&a);
 printf ("enter beginning balance :");
 scanf ("%f", &b_b);
 printf ("enter total charge :");
 scanf ("%f", &t_c1);
 printf ("enter total credits :");
 scanf ("%f", &t_c2);
 printf ("enter credit limit :");
 scanf ("%f", &c_l);
 b=b_b + t_c2 ;
 if (b>c_l)
 {
  printf ("Account :%f\n",a);
  printf ("Credit limit :%.2f\n", c_l);
  printf ("Balance :%.2f\n", b);
  printf ("Credit limit Exceeded\n");
 }
}
}
 现在是输入 a=0 还会继续一轮操作才会停止，
怎样使a=0时直接不继续？

在scanf ("%f",&a);加上
if(a == 0)
break;
即可

谢谢了，不用break 还有办法吗 ？

还可以用return

break和continue是最直接的方法，如果不想用你可以这样试试，不过个人认为这个方法不好，建议不要用
#include <stdio.h>
main ()
{
float a, b_b, t_c1, t_c2, c_l, b;
printf ("enter account number:");
scanf ("%f",&a);
printf ("enter beginning balance :");
scanf ("%f", &b_b);
printf ("enter total charge :");
scanf ("%f", &t_c1);
printf ("enter total credits :");
scanf ("%f", &t_c2);
printf ("enter credit limit :");
scanf ("%f", &c_l);
while (a != 0)
{
b=b_b + t_c2 ;
if (b>c_l)
{
  printf ("Account :%f\n",a);
  printf ("Credit limit :%.2f\n", c_l);
  printf ("Balance :%.2f\n", b);
  printf ("Credit limit Exceeded\n");
}
printf ("enter account number:");
scanf ("%f",&a);
printf ("enter beginning balance :");
scanf ("%f", &b_b);
printf ("enter total charge :");
scanf ("%f", &t_c1);
printf ("enter total credits :");
scanf ("%f", &t_c2);
printf ("enter credit limit :");
scanf ("%f", &c_l);
}
}

用 do{...} while;  结构