How to call a function on every element of a vector in C++

This post will discuss how to call a function on every element of a vector in C++.

1. Using `std::for_each`

The standard solution to call a given function on each of the elements in the specified range is using the std::for_each function. Following is a simple example demonstrating the usage of this function:

#include <iostream>

#include <vector>

#include <algorithm>

void increment(int &i) {

i++;

}

int main()

{

std::vector<int> v = {1, 2, 3, 4, 5};

std::for_each(v.begin(), v.end(), &increment);

for (int i: v) {

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

}

return 0;

}

Download Run Code

Output:

2 3 4 5 6

This is equivalent to the following, which shortens the code with C++11 lambdas.

#include <iostream>

#include <vector>

#include <algorithm>

int main()

{

std::vector<int> v = {1, 2, 3, 4, 5};

std::for_each(v.begin(), v.end(), [&](int &i){

i++;

});

for (int i: v) {

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

}

return 0;

}

Download Run Code

Output:

2 3 4 5 6

2. Using `std::transform`

Another option is to use the std::transform standard algorithm, which applies a given function to elements of the specified range. It is defined in the header file <algorithm>, and can be invoked as follows:

#include <iostream>

#include <vector>

#include <algorithm>

int increment(int &i) {

return i + 1;

}

int main()

{

std::vector<int> v = {1, 2, 3, 4, 5};

std::transform(v.begin(), v.end(), v.begin(), &increment);

for (int i: v) {

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

}

return 0;

}

Download Run Code

Output:

2 3 4 5 6

The following code uses lambda expressions that were introduced with C++11.

#include <iostream>

#include <vector>

#include <algorithm>

int main()

{

std::vector<int> v = {1, 2, 3, 4, 5};

std::transform(v.begin(), v.end(), v.begin(), [&](int &i){

return i + 1;

});

for (int i: v) {

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

}

return 0;

}

Download Run Code

Output:

2 3 4 5 6

That’s all about calling a function on every element of a vector in C++.

How to call a function on every element of a vector in C++

1. Using std::for_each

2. Using std::transform

Share this:

1. Using `std::for_each`

2. Using `std::transform`