程序为什么会出错？

#include
#define MAX 500
void main()
{printf("\t\t\t\t\t数组\n求向量的和、差、点积。\n");
int i,j,n;
float a[MAX],b[MAX],c[MAX],d[MAX],dot_proc;
do
{printf("Input the element number(<=%d<=0 to quit):\n");
scanf("%d",&n);
if(n<=0)
exit(-2);
printf("Input %d numbes for vector a:\n",n);
for(i=0;i<n;i++)
{scanf("%f",&a[i]);
}
printf("Input %d number for vector b:\n",n);
for(i=0;i<n;i++)
{scanf("%f",&b[i]);
}
dot_proc=0.0;
for(i=0;i<n;i++)
{c[i]=a[i]+*(b+i);
(d+i)=a[i]-b[i];
dot_proc+=(a+i)*b[i];
}
printf("\n The sum of the vectors is as follows:\n");
for(i=0;i<n;i++)
{printf("%10.2f",c[i]);
if((i+i)%6==0)
printf("\n");
}
printf("\nThe difference of the vectors is as follows:\n");
for(i=0;i<n;i++)
{printf("%10.2f",d[i]);
if((i+1)%6==0)
printf("\n");
}
printf("\nThe dot product is %10.4f\n",dot_proc);
}while(1);
}

为什么会出现error C2065: 'exit' : undeclared identifier的问题？

有变量未声明/定义。。。

 加上 #include <stdlib.h>