c语言程序设计的疑惑,找不到graphics.h

#include"graphics.h"
#include"stdio.h"
#include"conio.h"
#include"stdlib.h"
#include"math.h"
#include"time.h"
#define SCREEN_WIDTH 800
#define SCREEN_HEIGHT 600
#define MAXCOLOR 16
#define MOD 100
#define SUM 30000
void DrawMandelbrot(int x_top,int y_top,int x_bottom,int y_bottom)
{
int np,nq,k;
int ViewPortX=x_bottom-x_top,
ViewPortY=y_bottom-y_top;
double x[MAXCOLOR+1],y[MAXCOLOR+1];
double r,p,q,pmin=-2.25,pmax=0.75,qmin=-1.5,qmax=1.5;
double deltap=(pmax-pmin)/(double)(ViewportX-1),deltaq=(qmax-qmin)/(double)(ViewportY-1);
for(np=0;np<ViewportX,np++)
for(nq=0;nq<ViewportY;nq++)
{
k=0;
p=pmin+np*deltap;
q=qmin+nq*deltaq;
x[0]=y[0]=0;
do
{
x[k+1]=x[k]*x[k]-y[k]*y[k]+p;
y[k+1]=2*x[k]*y[k]+q;
k++;
r=x[k]*x[k]+y[k]*y[k];