使用位运算现实二进制
#include
char * itobs (int n , char *ps );
void show_bstr(const char *);
int invert_end ( int num,int bits);
int main()
{
char bin_str[8 * sizeof(int) + 1];
int number ;
printf("enter integers and see them in binary ");
puts("non - numeric input terminates program");
while (scanf("%d",&number) == 1) {
itobs(number, bin_str);
printf("%d is \n",number);
show_bstr(bin_str);
putchar('\n');
// number = invert_end(number , 4);
// printf("inverting the last b bits gives \n");
// show_bstr(itobs(number, bin_str));
}
}
char *itobs (int n ,char *ps)
{
int i;
static int size = 8 * sizeof(int);
for (i = size -1 ; i >= 0 ; i -- ,n >>= 1) {
ps[i] = (01 & n ) + '0' ;
}
ps[size]='\0';
return ps;
}
void show_bstr(const char *str)
{
int i = 0;
while (str[i]) {
putchar(str[i]);
if (++ i % 4 == 0 && str[i]) {
putchar(' ');
}
}
}
使用位操作符来显示二进制
#include
char * itobs (int n , char *ps );
void show_bstr(const char *);
int invert_end ( int num,int bits);
int main()
{
char bin_str[8 * sizeof(int) + 1];
int number ;
printf("enter integers and see them in binary ");
puts("non - numeric input terminates program");
while (scanf("%d",&number) == 1) {
itobs(number, bin_str);
printf("%d is \n",number);
show_bstr(bin_str);
putchar('\n');
number =invert_end(number , 4);
printf("inverting the last b bits gives \n");
show_bstr(itobs(number, bin_str));
putchar('\n');
}
puts("Bye");
}
char *itobs (int n ,char *ps)
{
int i;
static int size = 8 * sizeof(int);
for (i = size -1 ; i >= 0 ; i -- ,n >>= 1) {
ps[i] = (01 & n ) + '0' ;
}
ps[size]='\0';
return ps;
}
void show_bstr(const char *str)
{
int i = 0;
while (str[i]) {
putchar(str[i]);
if (++ i % 4 == 0 && str[i]) {
putchar(' ');
}
}
}
int invert_end(int num,int bits)
{
int mask = 0;
int bitval = 1;
while(bits-- >0) {
mask |= bitval;
bitval <<=1;
}
return num^mask ;
}
定义和使用字段
#include
#define YES 1
#define NO 0
#define SOLID 0
#define DOTTED 1
#define DASHED 2
#define BLUE 4
#define GREEN 2
#define RED 1
#define BLACK 0
#define YELLOW (RED | GREEN)
#define MAGENTA (RED | BLUE)
#define CYAN (GREEN | BLUE)
#define WHITE (RED | GREEN | BLUE)
const char *colors[8] ={"black","red","green","yellow","blue","magenta","cyan","while"};
struct box_props{
unsigned intopaque :1;
unsigned intfill_color :3;
unsigned int :4;
unsigned intshow_border :1;
unsigned int border_color :3;
unsigned int border_style :1;
unsigned int :1;
};
void show_settings (const struct box_props *pb);
int main(void)
{
struct box_props box= {YES , YELLOW ,YES,GREEN,DASHED};
printf("Orginal box settings : \n");
show_settings(&box);
}
void show_settings (const struct box_props *pb)
{
printf("box is %s \n",pb->opaque ==YES ? "opaue": "transparent");
printf("the fill color is %s .\n",colors [pb->fill_color]);
printf("Boreder %s \n",pb->show_border == YES? "shown":"notshwn");
printf("the border color is %s \n ",colors[pb->border_color]);
printf("the border style is");
switch (pb->border_style) {
case SOLID:
printf("solid \n ");
break;
case DOTTED:
printf("dotted \n ");
break;
case DASHED :
printf("dashed \n ");
break;
default:
printf("unknown type \n");
}
}
位字段运算
#include
#define YES 1
#define NO 0
#define SOLID 0
#define DOTTED 1
#define DASHED 2
#define BLUE 4
#define GREEN 2
#define RED 1
#define BLACK 0
#define YELLOW (RED | GREEN)
#define MAGENTA (RED | BLUE)
#define CYAN (GREEN | BLUE)
#define WHITE (RED | GREEN | BLUE)
#define OPAQUE 0X1
#define FILL_BLUE 0X8
#define FILL_GREEN 0X4
#define FILL_RED 0X2
#define FILL_MASK 0XE
#define BORDER 0X100
#define BORDER_BLUE 0X800
#define BORDER_GREEN 0X400
#define BORDER_RED 0X200
#define BORDER_MASK 0XE00
#define B_SOLID 0
#define B_DOTTED 0X1000
#define B_DASHED 0X2000
#define STYLE_MASK 0X3000
const char *colors[8] ={"black","red","green","yellow","blue","magenta","cyan","while"};
struct box_props{
unsigned intopaque :1;
unsigned intfill_color :3;
unsigned int :4;
unsigned intshow_border :1;
unsigned int border_color :3;
unsigned int border_style :2;
unsigned int :2;
};
union Views
{
struct box_props st_view;
unsigned int ui_view;
};
void show_settings (const struct box_props *pb);
void show_settings1(unsigned short);
char * itobs(int n,char * ps);
int main(void)
{
union Views box = {{ YES, YELLOW,YES,GREEN,DASHED}};
char bin_str[8 * sizeof(unsigned int) +1];
printf("Original box settings \n");
show_settings(&box.st_view);
printf("\n Box setting using unsigned int view \n");
show_settings1(box.ui_view);
printf("bits are %s \n",itobs(box.ui_view, bin_str));
box.ui_view &= ~FILL_MASK;
box.ui_view |= (FILL_BLUE | FILL_GREEN);
box.ui_view ^= OPAQUE;
box.ui_view |= BORDER_RED;
box.ui_view &= ~STYLE_MASK;
box.ui_view |= B_DOTTED;
printf("\n modified box sttings\n");
show_settings(&box.st_view);
printf("\n Box settings using unsigned\n");
show_settings1(box.ui_view);
printf("bits are %s\n",itobs(box.ui_view, bin_str));
return 0;
}
char *itobs(int n , char* ps)
{
int i ;
static int size = 8 * sizeof(unsigned int );
for (i = size -1 ; i >= 0; i -- ,n>>= 1) {
ps[i] = (01 & n ) + '0';
}
ps[size] ='\0';
return ps;
}
void show_settings (const struct box_props *pb)
{
printf("box is %s \n",pb->opaque ==YES ? "opaue": "transparent");
printf("the fill color is %s .\n",colors [pb->fill_color]);
printf("Boreder %s \n",pb->show_border == YES? "shown":"notshwn");
printf("the border color is %s \n ",colors[pb->border_color]);
printf("the border style is");
switch (pb->border_style) {
case SOLID:
printf("solid \n ");
break;
case DOTTED:
printf("dotted \n ");
break;
case DASHED :
printf("dashed \n ");
break;
default:
printf("unknown type \n");
}
}
void show_settings1(unsigned short us)
{
printf("box is %s \n",us& OPAQUE == OPAQUE? "opaque" : "transparent");
printf("the fill color is %s \n", colors[(us>>1) &7]);
printf("Border %s \n",us & BORDER == BORDER? "shown" : "not shown");
printf("the border style is");
switch (us & STYLE_MASK ) {
case B_SOLID:
printf("solid.\n");
break;
case B_DOTTED:
printf("dotted \n ");
break;
case B_DASHED:
printf("dashed \n ");
break;
default:
printf("unknown type \n");
}
printf("the border color is %s \n",colors[(us>>9)& 07] );
}
#include
#define TWO 2
#define OW "Consistency is the last refuge of the unimagin\ tive. -Oscar Wilde"
#define FOUR TWO * TWO
#define PX printf("X is %d.\n",x)
#define FMT "X is %d.\n"
int main(void )
{
int x = TWO;
PX;
x =FOUR;
printf(FMT ,x);
printf("%s \n", OW);
printf("TWO : OW\n");
return 0;
}