算数移位与逻辑移位，栈实现二进制输出

A:算数移位与逻辑移位：

  1.算数左移同逻辑左移

  2.算数右移用符号位填

  3.逻辑右移用0填

B:负数用补码存储；

  -1 在计算机里的表示是全 1

C:

 

/*******摘至华为面试题********/
int main()
{
  char *p;
 // *p=-128; //输出-128
 *p=-130;
printf("%d",*p); // 输出126
return 0;
}

/*因为负数以补码形式存储，
 C 中char是8位，最高位被去掉，*/
/***************************/

 

/**********正常运行*************/
int x=7;
for(;x;) {
   x=x>>1;
}

/******************************/

/**************死循环**********/
int x=-4;
while(x<0) {
  x>>=1; // x 永远数负数，所以死循环
}

/******************************/

 

/**************************  正数二进制输出   **************************************/

 

#include <stdio.h>

#define STACK_INIT_SIZE 100
#define STACKINCREMENT 10
#define OK 1
#define ERROR 0
#define bit_0 (0x1<<0)

typedef char Elemtype;
typedef int Status;

typedef struct __stack {
    Elemtype *base;
    Elemtype *top;
    int stacksize;
} stack;

Status init_stack(stack *s) //初始化
{
    s->base=(Elemtype *)malloc(STACK_INIT_SIZE*sizeof(Elemtype));
    if(s->base==NULL)
        exit(-1);
    s->top=s->base;
    s->stacksize=STACK_INIT_SIZE;

    return OK;
}

Status stack_destory(stack *s) // 销毁栈
{
    if(NULL == s->base)
        return ERROR;
    free(s->base);
    return OK;
}

Status Push(stack *s,Elemtype e) // 进栈
{
    if((s->top - s->base)>= s->stacksize) {
        s->base=(Elemtype *)realloc(s->base,(s->stacksize+STACKINCREMENT)*sizeof(Elemtype));
        if(NULL == s->base)
            exit(-1);
        s->top=s->base+s->stacksize;
        s->stacksize +=STACKINCREMENT;
    }
    *s->top++=e;
    return OK;

}

Elemtype Pop(stack *s) { // 出栈
    Elemtype e;
    if(s->top == s->base)
        exit(-1);
    e=*(--s->top);
    return e;
}

int main()
{
    stack s;
    int x;
    Elemtype e;

    printf("请输入你要转换的数：");
    scanf("%d",&x);

    init_stack(&s);

    for(;x;) {
        if(x & bit_0)
            Push(&s,1);
        else
            Push(&s,0);
        x=x>>1;
    }

    while(s.top != s.base)
    {
        e=Pop(&s);
        printf("%d",e);
    }

    return 0;

}