在文本文件中搜索某个单词 C++

Question

我正在尝试按项目的成分创建一个可搜索的食谱数据库。我正在尝试创建遍历字符串向量（其中保存了每种成分）的 for 循环并搜索文件并比较它们。现在，我只想让它输出“你好！”如果有比赛。经过我所有的摆弄，要么有 100 个 Hello!s（绝对不正确），要么没有。代码如下：

int main()
{
int y;
cout << "Hello! Welcome to Abby's Recipe Calculator." << endl << endl;
cout << "Please select an option: 1 to search by ingredient or 2 to browse recipes..." << endl;
cin >> y;

vector <string> ingreds;
ingreds.reserve(4); 

if (y == 1)
{
    ingredientvector(ingreds); // calls function to fill vector w/ ingredients
}
//else if (y == 2)
//{
//call recipe function... 
//}

Search x1(ingreds); //assigns ingredients to object vector

recipesearch(x1.getingreds());

system("pause");
return 0;
}

void ingredientvector(vector<string>& x)
 {
cout << "SEARCH BY INGREDIENT" << endl;
cout << "Please enter up to three ingredients... " << endl;

for (int i = 0; i < 4; i++)
{
    x.push_back("  ");
    getline(cin, x[i]);
    if (x[i] == "1")
    {
        break;
    }

}

  }

  void recipesearch(const vector<string>& ingredientlist) //ifstream& recipes)
 {

ifstream myrecipes;
string line;
string ingredient;
myrecipes.open("recipes.txt");
if (myrecipes.is_open())
{
    for (int i = 0; i < 4; i++)
    {
        ingredient = ingredientlist[i];
        while(getline(myrecipes, line)){
            if (ingredient == line)
            {
                cout << "Hello!" << endl;
            }
            else
            {
                break;
            }
        }
    }   
}
else cout << "Unable to open recipe file!";

myrecipes.close();
}

以下是使用的配方示例：

Cheese-y Ramen

Prep Time: 5 minutes
Cook Time: 20 minutes
Total Time: 25 minutes
Servings: 2
Ingredients:
8 oz cheddar cheese
1 tablespoon cornstarch
¾ cup milk
2 packages ramen noodles
Directions:
1. Grate cheddar cheese and add with cornstarch into a small bowl
2. Combine with milk in a medium saucepan and cook on medium to low heat until consistent. Keep warm until serving.
3. In a separate pan boil ramen noodles. Set aside the included flavor packets.
4. Once boiling, drain the noodles and combine with cheese.
Recipe from Buzzfeed

Answer 1

这会将整个配方文件读入一个字符串，然后在字符串中查找每种成分。注意：这是非常暴力的。它很快，但不会很准确。例如，如果在侧边栏中提及奇多，而不是在食谱本身中，它们仍会被列出。

归功于它的到期，这个答案提升了从Read whole ASCII file into C++ std::string批发读取的文件

void recipesearch(const vector<string>& ingredientlist)
{

    ifstream myrecipes;
    string file;
    myrecipes.open("recipes.txt");
    if (myrecipes.is_open())
    {
        // read entire file into string
        myrecipes.seekg(0, std::ios::end);
        file.reserve(myrecipes.tellg());
        myrecipes.seekg(0, std::ios::beg);

        file.assign((std::istreambuf_iterator<char>(myrecipes)),
                    std::istreambuf_iterator<char>());

        // look inside file string for each ingredient
        for (const string & ingredient: ingredientlist)
        {

            if (file.find(ingredient) != file.npos)
            { // found ingredient in file
                cout << ingredient << endl;
            }
        }
    }
    else
        cout << "Unable to open recipe file!";

}

警告：您将从网络上提取的许多文件都以多字节字符集编码以获得更漂亮的结果和国际化，而不是大多数标准 C++ 工具默认使用的 7 位 ASCII，包括上面示例代码中使用的那些。

正确解释可能使用的多个多字节字符集中的哪一个以及如何使用它们本身就是一个讨论主题，但出于此任务的目的，OP 可能能够确保所有输入文件都与ASCII 编码。

Answer 2

尝试像这样反转 while 和 for 循环：

...the code before your for loop    
while(getline(myrecipes, line))
{
    for (int i = 0; i < 4; i++)
    {
        ingredient = ingredientlist[i];
        if (ingredient == line)
        {
            cout << "Hello!" << endl;
        }
        else
        {
            break;
        }
    }
}
...the code after your for loop