函数名: setgraphmode 
 功  能: 将系统设置成图形模式且清屏 
 用  法: #include <graphics.h> 
         void far setgraphmode(int mode); 
 程序例: 
#include <graphics.h> 
 #include <stdlib.h> 
 #include <stdio.h> 
 #include <conio.h> 
int main(void) 
 { 
    /* request auto detection */ 
    int gdriver = DETECT, gmode, errorcode; 
    int x, y; 
   /* initialize graphics and local variables */ 
    initgraph(&gdriver, &gmode, ""); 
   /* read result of initialization */ 
    errorcode = graphresult(); 
    if (errorcode != grOk)  /* an error occurred */ 
    { 
       printf("Graphics error: %s\n", grapherrormsg(errorcode)); 
       printf("Press any key to halt:"); 
       getch(); 
       exit(1); /* terminate with an error code */ 
    } 
   x = getmaxx() / 2; 
    y = getmaxy() / 2; 
   /* output a message */ 
    settextjustify(CENTER_TEXT, CENTER_TEXT); 
    outtextxy(x, y, "Press any key to exit graphics:"); 
    getch(); 
   /* restore system to text mode */ 
    restorecrtmode(); 
    printf("We're now in text mode.\n"); 
    printf("Press any key to return to graphics mode:"); 
    getch(); 
   /* return to graphics mode */ 
    setgraphmode(getgraphmode()); 
   /* output a message */ 
    settextjustify(CENTER_TEXT, CENTER_TEXT); 
    outtextxy(x, y, "We're back in graphics mode."); 
    outtextxy(x, y+textheight("W"), "Press any key to halt:"); 
   /* clean up */ 
    getch(); 
    closegraph(); 
    return 0; 
 }