How to Initialize a Vector with Default Values in C++? Last Updated : 25 Nov, 2024 Summarize Comments Improve Suggest changes Share Like Article Like Report Initialization is the process of assigning the value to the elements of vector. In this article, we will learn how to initialize the vector with default value in C++.The simplest method to initialize the vector with default value is by using constructor during declaration. Let’s take a look at a simple example: C++ #include <bits/stdc++.h> using namespace std; int main() { // Initialze vector with default value 9 vector<int> v(5, 9); for (auto i : v) cout << i << " "; return 0; } Output9 9 9 9 9 There are also some other methods in C++ to initialize the vector with default value. Some of them are as follows:Table of ContentUsing vector assign()Using fill()Using iota()Using Vector assign()The vector assign() method can also be used to assign the existing vector with specified size and some default value. C++ #include <bits/stdc++.h> using namespace std; int main() { vector<int> v; // Initialze vector with default value 9 v.assign(5, 9); for (auto i : v) cout << i << " "; return 0; } Output9 9 9 9 9 Using fill()In this method, first we create the vector with specified size and then we fill the vector with default value using fill() method. C++ #include <bits/stdc++.h> using namespace std; int main() { vector<int> v(5); // Initialze vector with default value 9 fill(v.begin(), v.end(), 9); for (auto i : v) cout << i << " "; return 0; } Output9 9 9 9 9 Note: With this method, we can initialize the range of vector with default value.Using iota()If we want to initialize our vector with sequential default value, then simply we can use iota() method. C++ #include <bits/stdc++.h> using namespace std; int main() { vector<int> v(5); // Initialze vector with sequential default value // starting with 9 iota(v.begin(), v.end(), 1); for (auto i : v) cout << i << " "; return 0; } Output1 2 3 4 5 Comment More infoAdvertise with us Next Article How to Initialize a Vector with Default Values in C++? G gaurav472 Follow Improve Article Tags : C++ Programs C++ STL cpp-vector CPP Examples +1 More Practice Tags : CPPSTL Similar Reads C++ Programming Language C++ is a computer programming language developed by Bjarne Stroustrup as an extension of the C language. It is known for is fast speed, low level memory management and is often taught as first programming language. It provides:Hands-on application of different programming concepts.Similar syntax to 5 min read Non-linear Components In electrical circuits, Non-linear Components are electronic devices that need an external power source to operate actively. 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