题目和结果记录

偏执的太偏执、 2023-07-04 12:38 10阅读 0赞

## 计算转为二进制之后数字1的数目 ##

int func(int x)
    { 
        int count=0;
        while (x) { 
            count++;
            x=x&(x-1);
    
        }
        return count;
    
    }

## printf压栈顺序和指针，后++ ##

int arr[]={ 6,7,8,9,10};
        int *ptr=arr;
       // *(ptr++)+=123;//等于两句
        *(ptr)+=123;
        ptr++;
        for (int i=0;i<5;i++) { 
            printf("%d\n",arr[i]);
        }
    
        printf("%d\n",*ptr);
        printf("%d,%d\n",*ptr,*(++ptr));
    
    
        return 0;

![上述代码结果][20200210223116830.png]

## c++引用 ##

#include <iostream>
     
    using namespace std;
     
    int main ()
    { 
       // 声明简单的变量
       int    i;
       double d;
     
       // 声明引用变量
       int&    r = i;
       double& s = d;
       
       i = 5;
       cout << "Value of i : " << i << endl;
       cout << "Value of i reference : " << r  << endl;
     
       d = 11.7;
       cout << "Value of d : " << d << endl;
       cout << "Value of d reference : " << s  << endl;
       
       return 0;
    }

Value of i : 5
    Value of i reference : 5
    Value of d : 11.7
    Value of d reference : 11.7

## 类型转换 ##

float a=1.0f;
        cout<<(int)a<<endl;
        cout<<&a<<endl;
        //cout<<(int)&a<<endl;
        cout<<(int&)a<<endl;
        cout<<boolalpha<<((int)a == (int&)a)<<endl;//将0/1打印成bool或者false
    
        float b=0.0f;
        cout<<(int)b<<endl;
        cout<<&b<<endl;
        //cout<<(int)&a<<endl;
        cout<<(int&)b<<endl;
        cout<<boolalpha<<((int)b == (int&)b)<<endl;//将0/1打印成bool或者false

![在这里插入图片描述][20200210225052813.png]

[20200210223116830.png]: https://img-blog.csdnimg.cn/20200210223116830.png
[20200210225052813.png]: https://img-blog.csdnimg.cn/20200210225052813.png