C&C++动态创建数组

#include 
using namespace std;

int main(){
    int *pi1 = new int;  //创建int指针
    int *pi2 = new int(2);  //创建int指针并初始化为2
    int *pi3 = new int[3];  //创建3个int指针
    
    delete pi1;
    delete pi2;
    delete [] pi3;
    return 0;
}

#include 
using namespace std;
struct Matrix{
    int width;
    int height;
    float *elements;
}

int main(){
    int w = 4, h = 2;
    Matrix *A;
    A = (Matrix*)malloc(sizeof(Matrix));
    A->width = w;
    A->height = h;
    A->elements = (float*)malloc(A->width * A->height * sizeof(float));
    
    free(A->elements);
    free(A);
    
    // c++
    // Matrix *A = new Matrix;
    // A->height = h;
    // A->width = w;
    // A->elements = new float[A->width * A->height];
    
    // delete [] A->elements;
    // delete A;
    return 0;
}

#include  
#include  
// 二维指针
int main()  
{  
    int **a;  //用二级指针动态申请二维数组  
    int i, j;  
    int m = 4, n = 2;
    a=(int**)malloc(sizeof(int*) * m);  
    for(i = 0; i < m; i++)  
    　　a[i]=(int*)malloc(sizeof(int) * n);  
    for(i = 0; i < m; i++)  
    　　for(j = 0; j < n; j++)  
    　　　　printf("%pn",&a[i][j]);     //输出每个元素地址，每行的列与列之间的地址时连续的，行与行之间的地址不连续  
    for(i = 0; i < m; i++)  
    　　free(a[i]);  
    free(a);  
    return 0;  
}

#include  
#include  
// 数组指针
int main()  
{  
    int i,j;  
    int m = 4;
    const int n = 2;
    //申请一个4行2列的整型数组  
    int(*a)[n] = (int(*)[n])malloc(sizeof(int) * m * n); 
    for(i = 0; i < m; i++)  
        for(j = 0; j < n; j++)  
           printf("%pn",&a[i][j]);  //输出数组每个元素地址，每个元素的地址是连续的  
    free(a);  
    return 0;  
}

#include
using namespace std;

int main()
{
    int row = 4, col = 2;
    //为行指针分配空间 
    int **arr = new int *[row];    
    for(int i = 0; i < row; i++)
         arr[i]= new int[col];//为每行分配空间（每行中有col个元素） 
    
    //释放二维数组（反过来） 
    for(int i = 0;i < row;i++)
        delete [] arr[i]; 
    delete [] arr;
    return 0;
}