C++双阵列初始化错误

Question

我有这个C++程序：

int box[9][9]; 
box = { {solution[0][0],solution[0][1],solution[0][2],solution[1][0],solution[1][1],solution[1][2],solution[2][0],solution[2][1],solution[2][2]}, 
          {solution[0][3],solution[0][4],solution[0][5],solution[1][3],solution[1][4],solution[1][5],solution[2][3],solution[2][4],solution[2][5]}, 
          {solution[0][6],solution[0][7],solution[0][8],solution[1][6],solution[1][7],solution[1][8],solution[2][6],solution[2][7],solution[2][8]}, 
          {solution[3][0],solution[3][1],solution[3][2],solution[4][0],solution[4][1],solution[4][2],solution[5][0],solution[5][1],solution[5][2]}, 
          {solution[3][3],solution[3][4],solution[3][5],solution[4][3],solution[4][4],solution[4][5],solution[5][3],solution[5][4],solution[5][5]}, 
          {solution[3][6],solution[3][7],solution[3][8],solution[4][6],solution[4][7],solution[4][8],solution[5][6],solution[5][7],solution[5][8]}, 
          {solution[6][0],solution[6][1],solution[6][2],solution[7][0],solution[7][1],solution[7][2],solution[8][0],solution[8][1],solution[8][2]}, 
          {solution[6][3],solution[6][4],solution[6][5],solution[7][3],solution[7][4],solution[7][5],solution[8][3],solution[8][4],solution[8][5]}, 
          {solution[6][6],solution[6][7],solution[6][8],solution[7][6],solution[7][7],solution[7][8],solution[8][6],solution[8][7],solution[8][8]}}; 

我得到的错误是：

error: assigning to an array from an initializer list 

这是什么意思？

Answer 1

初始化程序已声明变量时使用：

int box[9][9]= { {solution[0][0],solution[0][1],solution[0][2],solution[1][0],solution[1][1],solution[1][2],solution[2][0],solution[2][1],solution[2][2]}, 
          {solution[0][3],solution[0][4],solution[0][5],solution[1][3],solution[1][4],solution[1][5],solution[2][3],solution[2][4],solution[2][5]}, 
          {solution[0][6],solution[0][7],solution[0][8],solution[1][6],solution[1][7],solution[1][8],solution[2][6],solution[2][7],solution[2][8]}, 
          {solution[3][0],solution[3][1],solution[3][2],solution[4][0],solution[4][1],solution[4][2],solution[5][0],solution[5][1],solution[5][2]}, 
          {solution[3][3],solution[3][4],solution[3][5],solution[4][3],solution[4][4],solution[4][5],solution[5][3],solution[5][4],solution[5][5]}, 
          {solution[3][6],solution[3][7],solution[3][8],solution[4][6],solution[4][7],solution[4][8],solution[5][6],solution[5][7],solution[5][8]}, 
          {solution[6][0],solution[6][1],solution[6][2],solution[7][0],solution[7][1],solution[7][2],solution[8][0],solution[8][1],solution[8][2]}, 
          {solution[6][3],solution[6][4],solution[6][5],solution[7][3],solution[7][4],solution[7][5],solution[8][3],solution[8][4],solution[8][5]}, 
          {solution[6][6],solution[6][7],solution[6][8],solution[7][6],solution[7][7],solution[7][8],solution[8][6],solution[8][7],solution[8][8]}}; 

Answer 2

该C++错误：

error: assigning to an array from an initializer list 

引起，因为你正在试图与一个初始化其是分配一个数组不允许。初始化发生在创建数组时创建数组并将其值推入其中。当数组已经被创建并且新的值被放入时，分配发生。在初始化或分配过程中您可以执行的操作有所不同。

下面是导致上述错误的简单代码：

#include <cstdlib> 
#include <iostream> 
using namespace std; 
int main(int argc, char** argv) { 
    int myarray [] = {1,2,4}; 
    myarray [] = {2,5,9}; 
    //error, cannot assign with an initializer. 
    //You can't initialize an array that's already been initialized. 
    return 0; 
} 

如果你想在那里给力新价值，尝试std::copy：

int myarray [] = {1,2,3,4}; 
int newarray [] = {2,5,9,12}; 

//copy the first 4 elements from newarray into newarray 
std::copy(newarray, newarray + 4, myarray); 

for(int x = 0; x < 4; x++){ 
    cout << myarray[x] << ","; 
} 

它打印：2,5,9,12,

但是你应该问自己为什么你编程接近金属 像那样。

考虑使用std :: vector的，而不是：

#include <iostream> 
#include <vector> 
using namespace std; 
int main(int argc, char** argv) { 
    vector<int> array; 
    cout << "size is: " << array.size() << endl; 
    array.push_back(42); 
    cout << "size is: " << array.size() << endl; 
    cout << "data items: " << array.at(0) << endl; 
    array.insert(array.begin(), 5); 
    array.insert(array.end(), 20); 
    cout << "size is: " << array.size() << endl; 
    int len = array.size(); 
    for(int x = 0; x < array.size(); x++){ 
     cout << "data item: " << array.at(x) << endl; 
    } 
    return 0; 
} 

打印此：

size is: 0 
size is: 1 
data items: 42 
size is: 3 
data item: 5 
data item: 42 
data item: 20 

使用C++向量重新初始化列表：

#include <iostream> 
#include <vector> 
using namespace std; 
int main() 
{ 
    int foobar[3] = {1, 2, 3}; 
    std::vector<int> myvector(foobar, foobar + 3); 

    int moobar[3] = {4, 5, 6}; 
    myvector.assign(moobar, moobar + 3); 

    for(int x = 0; x < 3; x++) 
     cout << myvector[x]; 
}