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我在C++中实现mySQL并遇到问题。我得到一个seg故障。我不知道为什么。C++ Seg中的MySQL错误
希望有人知道发生了什么事。
该seg故障似乎发生在MYSQL_ROW productList;
行之后的某处,但我无法确定哪些位置在哪里。
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);
}
您从不真正检查查询(或init)是否成功,以及在调用mysql_store_result之后resSetProduct是否为非null。另外,在'\'之后/之前还有一些额外的空格,是故意的吗? – PhilMasterG
向前走,并删除多余的空间。不会这样做(检查查询或resSetProduct)导致seg故障?我正在使用我为同一个班级编写的其他方法,并且他们工作得很好。我不是100%熟悉这一点。 – kevin
你应该检查'mysql_real_query'是否返回零。如果没有,'mysql_store_result'将返回NULL,'mysql_num_rows'可能会因段错误而失败。 – PhilMasterG