C ++ Seg Fault中的MySQL

Question

我正在C ++中实现mySQL，但遇到了问题。 我遇到了段错误。 我不确定为什么。

希望有人会知道发生了什么事。
seg错误似乎发生在MYSQL_ROW productList;之后的MYSQL_ROW productList; 行，但是我无法指出。

void Receiving::getProduct(const string productToReturn) { 
MYSQL *connect, mysql;                  //Pointers to MySQL
connect = mysql_init(&mysql);           // Initialize the connections
int totalRows = 0;

connect = mysql_real_connect(connect,SERVER,USER,PASSWORD,DATABASE,0,NULL,0);  //Connect to database 

if(connect) {                           //If connection successful
    string sqlQuery;                    //will hold query

    MYSQL_RES *resSetProduct;           //define product result set
    MYSQL_ROW productList;              //define row for product

    sqlQuery = "SELECT * FROM Inventory WHERE item_id = \' "; //Create query with desired product id
    sqlQuery += productToReturn;
    sqlQuery += " \'";

    mysql_query(connect, sqlQuery.c_str());                                    // Send query to the database
    resSetProduct = mysql_store_result(connect);                               // Receive the result and store it in resSetProduct
    totalRows = mysql_num_rows(resSetProduct);                                 // count of stored rows

    if(totalRows == 0){                                                        //nothing found
        cout << "Sorry! No inventory found for that product!" << endl;
    }
    else {
        cout << "Product Id     In Stock" << endl;

        while( (productList = mysql_fetch_row(resSetProduct)) != NULL ) {      //printout the products
            cout << productList[0] << "    " << productList[1] << endl;
        }
    }
    mysql_free_result(resSetProduct);
}
else                                                                           //Failed to connect
    cerr << "Failed To Connect!";

mysql_close(connect); 
} 

Answer 1

您应该检查mysql_query返回零。 如果不是，则mysql_store_result将返回NULL，并且mysql_num_rows可能会因段错误而失败。

如果mysql_query返回非零值，则可以根据mysql文档检查错误代码，例如。 此处： MySQL mysql_query

清除这些错误后， mysql_num_rows不应再进行segfault。