C++錯誤：<project_name>觸發了一個斷點

Question

如何解決這個錯誤，當我運行和關閉這個項目？ 我寫了一個C++程序，它有這個錯誤： 觸發了一個斷點。

int num = 0; 
string **board = new string*[num]; 

cin >> num; 
system("cls"); 
for (int i = 0; i < num; i++) 
    board[i] = new string[num]; 

for (int i = 0; i < num; i++) 
    for (int j = 0; j < num; j++) 
     board[i][j]='_'; 


for (int i = 0; i < num; i++) 
{ 
    if(i!=0) 
    cout << endl<< endl<<endl<< endl; 
    for (int j = 0; j < num; j++) 
     cout << board[i][j]<<"    "; 
} 




cin.get(); 
cin.get(); 
for (int i = 0; i < num; i++) 
    delete[] board[i]; 
delete[] board; 
return 0; 

Answer 1

聲明

string **board = new string*[num];

需要被定位後你cin >> num;閱讀。

否則你試圖分配一個零長度的指針數組;這在C++中沒有很好的定義。

繼續前進，您可能會發現將整個板作爲單個std::vector<std::string>進行建模會更簡單，這將大大簡化內存管理。

Answer 2

int num = 0; 
cin >> num; 
string *board = new string[num]; // here 
system("cls"); 
for (int i = 0; i < num; i++) 
    board[i] = string(n,'_'); 
for (int i = 0; i < num; i++) 
{ 
    if(i!=0) 
    cout << endl<< endl<<endl<< endl; 
    for (int j = 0; j < num; j++) 
     cout << board[i][j]<<"    "; 
} 
cin.get(); 
cin.get(); 

delete[] board; 
return 0; 

Strings and containers allocate/deallocate automatically. However, a container of pointers doesn't free up what those pointers point to. We have to loop through those to free them.

我剛纔簡單的代碼位。