C語(yǔ)言函數(shù)大全(i開(kāi)頭)

函數(shù)名: imagesize
    功 能: 返回保存位圖像所需的字節(jié)數(shù)
    用 法: unsigned far imagesize(int left, int top, int right, int bottom);
    程序例:
    #include
    #include
    #include
    #include
    #define ARROW_SIZE 10
    void draw_arrow(int x, int y);
    int main(void)
    {
    /* request autodetection */
    int gdriver = DETECT, gmode, errorcode;
    void *arrow;
    int x, y, maxx;
    unsigned int size;
    /* 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 */
    }
    maxx = getmaxx();
    x = 0;
    y = getmaxy() / 2;
    /* draw the image to be grabbed */
    draw_arrow(x, y);
    /* calculate the size of the image */
    size = imagesize(x, y-ARROW_SIZE, x+(4*ARROW_SIZE), y+ARROW_SIZE);
    /* allocate memory to hold the image */
    arrow = malloc(size);
    /* grab the image */
    getimage(x, y-ARROW_SIZE, x+(4*ARROW_SIZE), y+ARROW_SIZE, arrow);
    /* repeat until a key is pressed */
    while (!kbhit())
    {
    /* erase old image */
    putimage(x, y-ARROW_SIZE, arrow, XOR_PUT);
    x += ARROW_SIZE;
    if (x >= maxx)
    x = 0;
    /* plot new image */
    putimage(x, y-ARROW_SIZE, arrow, XOR_PUT);
    }
    /* clean up */
    free(arrow);
    closegraph();
    return 0;
    }
    void draw_arrow(int x, int y)
    {
    /* draw an arrow on the screen */
    moveto(x, y);
    linerel(4*ARROW_SIZE, 0);
    linerel(-2*ARROW_SIZE, -1*ARROW_SIZE);
    linerel(0, 2*ARROW_SIZE);
    linerel(2*ARROW_SIZE, -1*ARROW_SIZE);
    }