Working with multi-dimensional vectors in programming can sometimes be challenging, especially when dealing with custom objects. In this blog post, we will explore how to find the index of a specific object within a 2D vector of custom objects in a simple and efficient manner.

Background

Before diving into the solution, let’s first define what a 2D vector is. A 2D vector, also known as a matrix, is a container that holds elements arranged in a rectangular grid format. Each element within the matrix can be accessed using its row and column indices.

The Problem

Let’s assume we have a 2D vector called matrix that contains custom objects of type MyObject. Our task is to find the index (row and column) of a specific MyObject within this matrix.

The Solution

To find the index of a specific object within a 2D vector, we need to iterate over each row and column of the vector until we find a match.

int findIndexOfObject(const std::vector<std::vector<MyObject>>& matrix, const MyObject& targetObject) {
    for (int row = 0; row < matrix.size(); ++row) {
        for (int col = 0; col < matrix[row].size(); ++col) {
            if (matrix[row][col] == targetObject) {
                return row * matrix[row].size() + col;
            }
        }
    }
    return -1; // Return -1 if the object is not found in the matrix
}

In the code snippet above, we define a function called findIndexOfObject that takes in the 2D vector matrix and the targetObject we are looking for. We iterate over each row and column using nested for loops, comparing each object with the targetObject. If a match is found, we calculate the linear index of the element using the formula row * matrix[row].size() + col. Finally, we return the index if a match is found or -1 if the object is not present in the matrix.

Usage Example

Let’s see how we can use the findIndexOfObject function to locate the index of a specific object within a 2D vector.

int main() {
    std::vector<std::vector<MyObject>> matrix = {
        {MyObject(1), MyObject(2), MyObject(3)},
        {MyObject(4), MyObject(5), MyObject(6)},
        {MyObject(7), MyObject(8), MyObject(9)},
    };

    MyObject target(5);
    int index = findIndexOfObject(matrix, target);

    if (index != -1) {
        std::cout << "The object is found at index " << index << std::endl;
    } else {
        std::cout << "Object not found in the matrix" << std::endl;
    }

    return 0;
}

In this example, we create a 2D vector matrix with custom objects, and we want to find the index of an object with value 5. After calling the findIndexOfObject function, we check if the returned index is -1 (indicating no match) or otherwise print the index.

Conclusion

Finding the index of a specific object within a 2D vector of custom objects can be achieved by iterating over each element until a match is found. By using the provided code snippet, you can easily locate the index and perform further operations on the desired object within the matrix. #programming #vectors