int getMaxInt1(){
  return ( 1 << 31 ) – 1; //优先级括号不能省略
}

int getMaxInt2(){
  return ~( 1 << 31 );
}

int getMaxInt3(){
  return ( 1 << -1 ) – 1;  //gcc 不支持
}

int getMaxInt4(){
  return ( (unsigned int) – 1 ) >> 1;
}

int getMinInt5(){
  return 1 << 31; //获取int类型的最小值
}

int getMinInt6(){
  return 1 << -1; //gcc 不支持
}

int getMaxLong(){
  return ((unsigned long) – 1 ) >> 1;
}

int getMinLong(){
  return 1 << 63;
}

int mulTwo(int n){
   return n << 1;
}

int divTwo(int n){
  return n >> 1;
}

int mulTwoPower(int n,int m){
 //n*(2^m)
  return n << m;
}

int divTwoPower(int n,int m){
 //n/(2^m)
  return n >> m;
}

bool isOddNumber(int n){
  return (n & 1) == 1;
}

void swap1(int a,int b){
 a ^= b;
 b ^= a;
 a ^= b;
 cout<<a<<” “<<b<<endl;
}

void swap2(int *a,int *b){
 (*a) ^= (*b) ^= (*a) ^= (*b);
}

int abs(int n){
  return (n^( n >> 31 )) -( n >> 31 );
}

int main(int argc,char *argv[])
{
   /*
    *位运算的20则
    * */
    int max1 = getMaxInt1();
    int max2 = getMaxInt2();
    int max3 = getMaxInt4();
    int min1 = getMinInt5();
    int min2 = getMinInt6();
    int max4 = getMaxLong();
    int min3 = getMinLong();
    int num1 = mulTwo(2);
    int num2 = divTwo(2);
    int num3 = mulTwoPower(2,1);
    int num4 = divTwoPower(2,1);
    int num5 = isOddNumber(4);
    int num6 = isOddNumber(3);
    int a=3;
    int b=4;
    int a1=3;
    int b1=4;
    a ^= b;
    b ^= a;
    a ^= b;
    //cout<<a<<”  “<<b<<endl;
    //cout<<max1<<” “<<max2<<” “<<max3<<endl;
    //cout<<min1<<” “<<min2<<endl;
    //cout<<max4<<endl;
    //cout<<min3<<endl;
    //cout<<num1<<” “<<num2<<endl;
    //cout<<num3<<” “<<num4<<endl;
    //cout<<num5<<” “<<num6<<endl;
    //swap1(a,b);
    //cout<<a<<” “<<b<<endl;
    //swap2(&a1,&b1);
    //cout<<a1<<” “<<b1<<endl;
    int abs1 = abs(-5);
    cout<<abs1<<endl;
    return 0;
}