Question

因此，基本上，我正在制作一个程序，用于存储学生信息以及学生在结构内部的得分。我需要帮助弄清楚如何将值存储到每个学生的矢量成绩中，因为有些学生每个人都有2-3个测试分数，并且所有信息都来自输入文件。

#include <iostream>
#include <iomanip>
#include <vector>
#include <string>
#include <fstream>
using namespace std;

// Structures
struct Scores
{
    int id;
    string course = "";
    int credit;
    int score;
};

struct Person
{
    int id;
    string name = "";
    string phone = "";
    vector<Scores> grades;
};

// Function prototypes
void displayOne(vector<Person>, int);

int main()
{
    ifstream inputFile;
    ifstream inputFile2;
    inputFile.open("StudentInfo.txt");
    inputFile2.open("StudentScores.txt");

    Scores tempScore;
    Person tempStudent;
    vector<Person> students;

    if (inputFile)
    {
        int value = 0;
        string name = "";
        string phone = "";
        while (inputFile >> value >> name >> phone)
        {

            tempStudent.id = value;
            tempStudent.name = name;
            tempStudent.phone = phone;
            students.push_back(tempStudent);
        }
    }
    else cout << "Error Opening StudentInfo.txt.. Try again." << endl;

    displayOne(students, 12546);
    displayOne(students, 15667);
    displayOne(students, 14388);

    inputFile.close();
    inputFile2.close();

//displayOne(15667);

//displayAll();

    return 0;

}

// Function definitions
void displayOne(vector<Person> students, int verifyID)
{
    bool foundID = false;
    int index = 0;
    for (int i = 0; i < students.size(); i++)
    {
        if (students[i].id == verifyID)
        {
            foundID = true;
            index = i;
        }

    }
    if (students[index].id == verifyID)
    {
        cout << "Student ID: " << students[index].id << " ";
        cout << "Student Name: " << students[index].name << " ";
        cout << "Student Phone: " << students[index].phone << " ";
        cout << "=================================";
        cout << endl;
        cout << students[index].grades[].course << endl;
    }
}

我需要能够调用一个函数使我能够引用<<学生[0]-学生人数，并显示他们参加的每个班级以及他们取得的分数等等。

Answer 1

看起来您可能必须使用ec2-user:~/environment/01-hw-saas/myrottenpotatoes $ cucumber features/AdMovie.feature Using the default profile... Feature: User can manually add movie Scenario: Add a movie # features/AdMovie.feature:3 Given I am on the RottenPotatoes home page # features/step_definitions/web_steps.rb:44 Missing template movies/index, application/index with {:locale=>[:en], :formats=>[:html], :variants=>[], :handlers=>[:erb, :builder, :raw, :ruby, :coffee, :jbuilder]}. Searched in: * "/home/ec2-user/environment/01-hw-saas/myrottenpotatoes/app/views" (ActionView::MissingTemplate) ./features/step_definitions/web_steps.rb:45:in `/^(?:|I )am on (.+)$/' features/AdMovie.feature:4:in `Given I am on the RottenPotatoes home page' When I follow "Add new movie" # features/step_definitions/web_steps.rb:56 Then I should be on the Create New Movie page # features/step_definitions/web_steps.rb:230 When I fill in "Title" with "Men In Black" # features/step_definitions/web_steps.rb:60 And I select "PG-13" from "Rating" # features/step_definitions/web_steps.rb:85 And I press "Save Changes" # features/step_definitions/web_steps.rb:52 Then I should be on the RottenPotatoes home page # features/step_definitions/web_steps.rb:230 And I should see "Men In Black" # features/step_definitions/web_steps.rb:105 Failing Scenarios: cucumber features/AdMovie.feature:3 # Scenario: Add a movie 1 scenario (1 failed) 8 steps (1 failed, 7 skipped) 0m0.063s ec2-user:~/environment/01-hw-saas/myrottenpotatoes $来将学生映射到分数，例如SQL联接。

当您遍历 StudentScores.txt 并将每个分数读入临时source 'https://rubygems.org' # Bundle edge Rails instead: gem 'rails', github: 'rails/rails' gem 'rails', '4.2.10' # Use sqlite3 as the database for Active Record gem 'sqlite3' # Use SCSS for stylesheets gem 'sass-rails', '~> 5.0' # Use Uglifier as compressor for JavaScript assets gem 'uglifier', '>= 1.3.0' # Use CoffeeScript for .coffee assets and views gem 'coffee-rails', '~> 4.1.0' # See https://github.com/rails/execjs#readme for more supported runtimes # gem 'therubyracer', platforms: :ruby # Use jquery as the JavaScript library gem 'jquery-rails' # Turbolinks makes following links in your web application faster. Read more: https://github.com/rails/turbolinks gem 'turbolinks' # Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder gem 'jbuilder', '~> 2.0' # bundle exec rake doc:rails generates the API under doc/api. gem 'sdoc', '~> 0.4.0', group: :doc group :development, :test do # Call 'byebug' anywhere in the code to stop execution and get a debugger console gem 'byebug' gem 'cucumber-rails', :require => false gem 'cucumber-rails-training-wheels' # some pre-fabbed step definitions gem 'database_cleaner' # to clear Cucumber's test database between runs gem 'capybara' # lets Cucumber pretend to be a web browser gem 'launchy' # a useful debugging aid for user stories end group :development do # Access an IRB console on exception pages or by using <%= console %> in views gem 'web-console', '~> 2.0' # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring gem 'spring' # Use Haml for templates gem 'haml' end时，您将不得不在id中找到与{{ 1}}。找到该学生后，您可以Scores临时评分。

类似

student

Documentation for std::find_if

students is a Lambda Expression。它提供了一种快速肮脏的功能，Scores::id会对其进行调用以测试是否找到了它。

您可能会发现std::map比push_back更有助于存储Scores tempscore; while (inputFile2 >> tempscore) // requires a >> overload for Scores, but here I'm // just using it as shorthand for "read in a Scores." // Strongly consider the >> overload though. { auto & id = tempscore.id; // make this c++11 proof. C++11 doesn't handle // capturing members // find student who matches id auto found = std::find_if(students.begin(), students.end(), [id] (const Student& s) { return s.id == id; }) if (found != students.end()) // actually found a match { found->grades.push_back(tempscore); // add score } else { // handle missing student. Log it and discard? Abort? Your call. } }。 [id] (const Student& s) { return s.id == id; }使查找像

一样简单

find_if

students非常适合简单的搜索，但在迭代方面却不如std::vector更好，而且开销更大，可以超过在短列表中节省的开销。如果学生名单很长，并且程序需要大量搜索std::map<id, Person> students;，请使用Scores tempscore; while (inputFile2 >> tempscore) { // find student who matches id try { students.at(tempscore.id).grades.push_back(tempscore); // add score } catch (const std::out_of_range &) { // handle missing student. } }。如果它需要扫描整个列表，那么最好使用std::map。

结构嵌套在另一个结构中作为矢量

1 个答案: