add nested vector cpp

To add a nested vector in C++, you can follow these steps:

  1. Declare the outer vector: Start by declaring the outer vector using the vector container from the standard library. You need to specify the type of elements the vector will hold. For example, to declare a vector of vectors of integers, you can use the following syntax:

cpp std::vector<std::vector<int>> nestedVector;

  1. Initialize the outer vector: After declaring the outer vector, you can initialize it by assigning values to it. You can do this using the assignment operator or by using the push_back() function. For example, to initialize the outer vector with three inner vectors, each containing four integers, you can use the following code:

cpp std::vector<std::vector<int>> nestedVector(3, std::vector<int>(4));

This code creates an outer vector of size 3, where each element is an inner vector of size 4.

  1. Accessing elements: To access elements in the nested vector, you can use the square bracket notation. The first index represents the outer vector's position, and the second index represents the inner vector's position. For example, to access the element at position [1][2], you can use the following code:

cpp int element = nestedVector[1][2];

This code retrieves the element at the second position in the outer vector and the third position in the inner vector.

  1. Modifying elements: To modify elements in the nested vector, you can also use the square bracket notation. For example, to change the value at position [0][1] to 42, you can use the following code:

cpp nestedVector[0][1] = 42;

This code modifies the element at the first position in the outer vector and the second position in the inner vector.

  1. Adding elements: To add elements to the nested vector, you can use the push_back() function. For example, to add a new inner vector containing three integers to the end of the outer vector, you can use the following code:

cpp nestedVector.push_back(std::vector<int>(3));

This code adds a new inner vector of size 3 to the end of the outer vector.

  1. Removing elements: To remove elements from the nested vector, you can use the erase() function. For example, to remove the second inner vector from the outer vector, you can use the following code:

cpp nestedVector.erase(nestedVector.begin() + 1);

This code removes the element at the second position in the outer vector.

These are the steps to add a nested vector in C++. Remember to include the necessary header file, <vector>, at the beginning of your code to use the vector container.