C语言学习记录——操作符详解知识点选记（算术操作符、单目操作符、移位操作符、关系操作符、逻辑操作符、条件操作符......）二

#include <stdio.h>
int main()
{
  int a = -1;
  //根据前面复习的知识点，易得
  //10000000000000000000000000000001 - 原码
  //11111111111111111111111111111110 - 反码
  //11111111111111111111111111111111 - 补码
  int b = ~a; //全部按位取反
  //b的表示应为：
  //00000000000000000000000000000000 
  //故将a按位取反之后赋值给b的值为0
  printf("%d\n", a);
  printf("%d\n", b);
  return 0;
}

#include <stdio.h>
int main()
{
  int a = 13;
  //00000000000000000000000000001101
  //把a的二进制中的第五位变为1
  a = a | (1 << 4);
  //00000000000000000000000000001101  (旧的a)
  //00000000000000000000000000010000  (1 << 4)
  //按位或之后
  //00000000000000000000000000011101  (新的a)
  printf("a = %d\n", a);
 
 
  //此时再把a的二进制中的第五位变回0
  a = a & ~(1 << 4);
  //00000000000000000000000000010000  (1 << 4)
  // 按位取反之后
  //11111111111111111111111111101111  (按位取反后的1 << 4)
 
  //00000000000000000000000000011101  (新的a)
  //11111111111111111111111111101111  (按位取反后的1 << 4)
  // 按位与之后
  //00000000000000000000000000001101  (重新得到了旧的a)
  printf("a = %d\n", a);
  
  return 0;
}

#include <stdio.h>
int main()
{
  int a = 10, b, c;
  b = a++;
  printf("后置\na = %d\nb = %d\n\n", a, b);
 
  a = 10;
  b = 0;
  c = ++a;
  printf("前置\na = %d\nc = %d\n", a, c);
  return 0;
}

#include <stdio.h>
int main()
{
    int a = 3,b = 0;
    b = (a > 5 ? 1 : -1);
    return 0;
}

#include <stdio.h>
int main()
{
    if(a > 5)
       b = 1;
    else
       b = -1;
    return 0;
}

#include <stdio.h>
int add(int a, int b)
{}
void test()
{}
int main()
{
  int a, b,c;
  c = add(a, b);
  test();
  return 0;
}

#include <stdio.h>
int main()
{
  //构建一个结构体
  struct student
  {
    int age;
    float weight;
    float high;
  }stu1,stu2,*p = NULL;
  //建立指针变量p存储stu1的地址
  p = &stu1;
 
  //分别使用两个结构成员操作符
  p->age = 18;
  p->weight = 50.00;
  p->high = 170.00;
  stu2.age = 20;
  stu2.weight = 60.00;
  stu2.high = 180.00;
  printf("age:%d\nweight:%.2f\nhigh:%.2f\n\n", p->age, p->weight, p->high);
  printf("age:%d\nweight:%.2f\nhigh:%.2f\n\n",stu2.age, stu2.weight, stu2.high);
  return 0;
}

#include <stdio.h>
int main()
{
  char a = 3, b = 127, c;
  c = a + b;
  //3的二进制序列为：
  //00000000000000000000000000000011
  //但a为char型，占用的字节长度为1,八个比特位
  //00000011  -  a
 
  //同理，b的二进制序列为
  //00000000000000000000000001111111
    //01111111  -  b
 
  //c = a + b中
  //00000000000000000000000000000011
  //00000000000000000000000001111111
  //相加，得
  //00000000000000000000000010000010
  //存储为char型
  //10000010  -  c
  printf("%d\n", c);
  //此处打印c是以int的形式
    //而c原本是char型，小于int长度
    //所以要进行整型提升
  //根据符号位进行整型提升，得
  //11111111111111111111111110000010  -  补码
  //11111111111111111111111110000001  -  反码
  //10000000000000000000000001111110  -  原码
  return 0;
}

#include <stdio.h>
int main()
{
  int i = 10;
  i = i-- - --i * (i = -3) * i++ + ++i;
  printf("i = %d\n", i);
  return 0;
}

#include <stdio.h>
int fun()
{
  static int count = 1;
  return ++count;
}
int main()
{
  int answer;
  answer = fun() - fun() * fun();
  printf("answer = %d\n", answer);
  return 0;
}

#include <stdio.h>
int main()
{
  int i = 1;
  int ret;
  ret = (++i) + (++i) + (++i);
  printf("ret = %d\n", ret);
  printf("i = %d\n", i);
  return 0;
}