Split a vector into sub-vectors of size n in C++

Write an algorithm to split a vector into sub-vectors of size n in C++.

Splitting a vector into sub-vectors of a specific size is very easy in C++. We start by determining the total number of sub-vectors of size n formed from the input vector. Then we iterate the given vector, and in each iteration of the loop, we process the next set of n elements and copy it to a new vector using the std::copy algorithm. We need to take special care about the boundary conditions.

#include <iostream>

#include <vector>

// Utility function to print a vector

template<typename T>

void print(std::vector<T> const &v)

{

for (auto &i: v) {

std::cout << i << ' ';

}

std::cout << std::endl;

}

// Split a vector into sub-vectors of size `n` in C++

int main()

{

// input vector of integers

std::vector<int> v = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

// split vector into sub-vectors each of size `n`

int n = 4;

// determine the total number of sub-vectors of size `n`

int size = (v.size() - 1) / n + 1;

// create an array of vectors to store the sub-vectors

std::vector<int> vec[size];

// each iteration of this loop process the next set of `n` elements

// and store it in a vector at k'th index in `vec`

for (int k = 0; k < size; ++k)

{

// get range for the next set of `n` elements

auto start_itr = std::next(v.cbegin(), k*n);

auto end_itr = std::next(v.cbegin(), k*n + n);

// allocate memory for the sub-vector

vec[k].resize(n);

// code to handle the last sub-vector as it might

// contain fewer elements

if (k*n + n > v.size())

{

end_itr = v.cend();

vec[k].resize(v.size() - k*n);

}

// copy elements from the input range to the sub-vector

std::copy(start_itr, end_itr, vec[k].begin());

}

// print the sub-vectors

for (int i = 0; i < size; i++) {

print(vec[i]);

}

return 0;

}

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Output:

1 2 3 4
5 6 7 8
9 10

That’s all about splitting a vector into sub-vectors of size n in C++.

Split a vector into sub-vectors of size n in C++

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