c语言指针及malloc申请内存问题

Question

void exchange(float *p ,float *q){
float a = *p;
*p = *q;
*q = a;
}

float a = 0;
float b = 0;
printf("请输入a = ");
scanf("%f",&a);
printf("请输入b = ");
scanf("%f",&b);

exchange(&a, &b);
printf("a = %f,b = %f", a, b);
为什么运行结果是这样:
请输入a = 559.4
请输入b = 66.4
结果:
a = 66.400002,b = 559.400024

Answer 1

没错啊。
记住：浮点数是有误差的。