C++ 中将一维数组转成多维的三种方式示例详解

#include <iostream>
int main() {
    int arr4[2] = {0, 12};
    int* p5 = reinterpret_cast<int*>(&arr4);
    cout << p5[1] << std::endl; 
    struct S1 { int a; } s1;
    s1.a  = 100;
    int* p1 = reinterpret_cast<int*>(&s1);
    cout << *p1;   
}
// 12
// 100

#include <iostream>
using namespace std;
int main()
{
    constexpr const unsigned long n = 8;
    float arr1[n] = {1.2f, 1.3f, 1.4f, 1.5f, 1.6f, 1.7f, 1.8f, 1.9f};
    float *arr = new float[n];
    for(int i = 0; i < n; i++) {
        arr[i] = arr1[i];
    }
    // 1.reinterpret_cast
    unsigned long I, J, K;
    I = 2;
    J = 2;
    K = 2;
    cout << arr[0] << endl;
    float (&arr3d)[I][J][K] = *reinterpret_cast<float (*)[I][J][K]>(arr);
    cout << arr3d[0][0][0] << endl;
}

float(*arr3d1)[I][J] = (float(*)[I][J])arr;
cout << arr3d1[0][0][0] << endl;

float (&arr3d2)[I][J][K] = *static_cast<float (*)[I][J][K]>(static_cast<void*>(arr));
cout << arr3d2[0][0][0] << endl;

float c[4] =  {1,2,3,4};
float (&b)[4] = *static_cast<float(*)[4]>(&c); 
cout<<b[1]<<endl;

float c[4] =  {1,2,3,4};
float (&b)[2][2] = *static_cast<float(*)[2][2]>(static_cast<void*>(&c)); 
float (&d)[2][2] = *reinterpret_cast<float(*)[2][2]>(&c); 
cout<<b[1][1]<<endl;