Question

我知道这个题目有些令人困惑，但我真的需要帮助。我需要在数组中找到一个包含许多字符串的字符串。如果找不到该字符串，则显示相应的消息。但是当我使用for循环时，它会为数组中的每个字符串显示此消息，虽然它也显示找到的字符串...但我希望你能理解我的意思和抱歉，如果我没有意义的话。这是我的代码：

void Store::search() {
        string name;
        cout << "Enter name of product you're searching: " << endl;
        getline(cin, name);

        for (int i = 0; i < quantity; i++) {
            if (name.compare(database[i].name) == 0){                           
            cout << "-------------<Product found!>-------------" << endl;
            cout << "name: " << database[i].name << endl;
            cout << "supplier: " << database[i].supplier << endl;
            cout << "available quantity: " << database[i].quantity<< endl;
            cout << "price per unit: " << database[i].price<< endl;
            cout << "------------------------------------------" << endl;
                }
            else
            {
                cout << "Product doesn't exist in database!" << endl;
            }
          }     

        }

该代码适用于搜索，但如何停止输出“产品在数据库中不存在！”对于未找到的数组中的每个项目（即使找到搜索项目）？

提前谢谢

Answer 1

您可以使用语句标记：

void Store::search() 
{
    string name;
    bool found = false
    cout << "Enter name of product you're searching: " << endl;
    getline(cin, name);

    for (int i = 0; i < quantity; i++) 
    {
        if (name.compare(database[i].name) == 0){                           
        cout << "-------------<Product found!>-------------" << endl;
        cout << "name: " << database[i].name << endl;
        cout << "supplier: " << database[i].supplier << endl;
        cout << "available quantity: " << database[i].quantity<< endl;
        cout << "price per unit: " << database[i].price<< endl;
        cout << "------------------------------------------" << endl;
        found = true;
        break;
    }

    if (!found)
       cout << "Product doesn't exist in database!" << endl;

}

Answer 2

您还可以使用std::find_if，这将使您的代码看起来像：

auto it = std::find_if(databases.begin(), databases.end(), [&name](const auto &database) {return name.compare(database.name) == 0; });
if (it != databases.end())
{
    cout << it->name << endl;
    cout << "found" << endl;
}
else
{
    cout << "not found" << endl;
}

一般来说，C ++提供了许多这样的功能，通常可以缩短代码，提高可读性并保证功能

Answer 3

你可以：
1.如果在for循环中找到该项，则将bool变量设置为true 2.添加break以便在找到项目时立即退出循环 3.删除else部分，因为它会打印出“产品在数据库中不存在！”如果项目不匹配，则为每个循环周期 4.在for循环之后，检查found是否为false以检查集合中是否存在项目

bool found = false;
for (int i = 0; i < quantity; i++)
{
    if (name.compare(database[i].name) == 0)
    {
        cout << "-------------<Product found!>-------------" << endl;
        cout << "name: " << database[i].name << endl;
        cout << "supplier: " << database[i].supplier << endl;
        cout << "available quantity: " << database[i].quantity<< endl;
        cout << "price per unit: " << database[i].price<< endl;
        cout << "------------------------------------------" << endl;
        found = true; // set "found" to true
        break; // add a break to immediately exit for loop when item is found
    }
  }
if (!found)
{
    cout << "Product doesn't exist in database!" << endl;
}

Answer 4

我假设您要搜索数据库中的产品并在找到时打印其详细信息。否则，您希望通知用户未找到该产品。如果我理解正确，那么你需要将'else语句移出＆＃39;对于＆＃39;循环，例如：

void Store::search() {
    string name;
    cout << "Enter name of product you're searching: " << endl;
    getline(cin, name);
    bool found = false;
    for (int i = 0; i < quantity; i++) {
        if (name.compare(database[i].name) == 0){                           
        cout << "-------------<Product found!>-------------" << endl;
        cout << "name: " << database[i].name << endl;
        cout << "supplier: " << database[i].supplier << endl;
        cout << "available quantity: " << database[i].quantity<< endl;
        cout << "price per unit: " << database[i].price<< endl;
        cout << "------------------------------------------" << endl;
        found = true;
        break;
        }
    }     
    if (!found)
    {
        cout << "Product doesn't exist in database!" << endl;
    }
}

如果您的数据库可能包含更多具有相同名称的产品，请删除＆＃39; break;＆＃39;言。

Answer 5

更“现代的C ++”方法是利用C ++算法（例如std::find_if），lambdas以及auto说明符。

例如（假设数据库是std :: vector或某种STL容器）：

auto it = std::find_if(database.begin(), database.end(), [&name](const auto& item) { return name.compare(item.name) == 0; });
if (it != database.end())
{
    cout << it->name << endl;
    cout << "found" << endl;
}
else
{
    cout << "not found" << endl;
}

C ++ String Array每个项目的搜索输出

5 个答案: