Question in solving errors in C++ in Visual Studio2022 - c++

Question

How to solve the following errors in this code in visual studio 2022 version: expected an identifier on line 33
identifier "otherUser" is undefined on line 33 expected a']' on line 33 identifier "ratings" is undefined on line 38 language feature 'structured bindings' requires compiler flag 'std:c++17' on line 33
#include <iostream>
#include <map>
#include <vector>
#include <cmath>
#include <xlnt/xlnt.hpp>
// Define a type alias for a map that maps a user ID to a vector of ratings
using UserRatings = std::map<int, std::vector<double>>;
// Define a function to calculate the cosine similarity between two users
double cosineSimilarity(const std::vector<double>& user1, const std::vector<double>& user2) {
// Initialize variables to store the dot product and the magnitudes of the vectors
double dotProduct = 0.0;
double magnitude1 = 0.0;
double magnitude2 = 0.0;
// Calculate the dot product and magnitudes of the vectors
for (size_t i = 0; i < user1.size(); i++) {
dotProduct += user1[i] * user2[i];
magnitude1 += user1[i] * user1[i];
magnitude2 += user2[i] * user2[i];
}
// Calculate and return the cosine similarity
return dotProduct / (sqrt(magnitude1) * sqrt(magnitude2));
}
// Define a function to predict the rating of a movie for a given user
double predictRating(const UserRatings& userRatings, int user, int movie) {
// Initialize variables to store the predicted rating and the sum of the similarities
double prediction = 0.0;
double sumSimilarities = 0.0;
// Iterate over all users in the userRatings map
for (const auto& [otherUser, ratings] : userRatings) {
// Skip the current user
if (otherUser == user) continue;
// Calculate the similarity between the current user and the other user
double similarity = cosineSimilarity(userRatings.at(user), ratings);
// If the similarity is positive, add it to the sum of similarities and
// add the other user's rating for the movie to the prediction
if (similarity > 0) {
sumSimilarities += similarity;
prediction += similarity * ratings[movie];
}
}
// Return the predicted rating for the movie
return prediction / sumSimilarities;
}
int main() {
// Load the data from an Excel file
xlnt::workbook workbook;
workbook.load("ratings.xlsx");
xlnt::worksheet sheet = workbook.active_sheet();
// Create a map of user ratings
UserRatings userRatings;
for (auto row : sheet.rows()) {
int user = row[0].value<int>();
std::vector<double> ratings;
for (auto cell : row) {
if (cell.column() == 1) continue;
ratings.push_back(cell.value<double>());
}
userRatings[user] = ratings;
}
// Predict the rating of movie 3 for user 1
double prediction = predictRating(userRatings, 1, 3);
std::cout << "Predicted rating for movie 3 by user 1: " << prediction << std::endl;
return 0;
}
I want to implement dataset from an excel file

Answer 1

In your code we could see that the code lacks the definition of the following variables, you need to define them according to your requirements.
feature 'structured bindings' requires compiler flag 'std:c++17' on
line 33
For this error, you need to right click on the project and select project properties, then set C++ Language Standard to c++17.